I have a full set of original FIA Relief stamped homologation set of documents and Special Tuning data/drawings.
After 1976 the gp2 rules altered very much and Triumph had to homologate a lot of parts that were legal under gp2 before 1976 and illegal after 1976. The four link rear suspension for example. Before 1976 pick up points and layout were free and after 1976 a gp2 car had to have the std pick up points for the suspension. The cheapest option was to use only gp1 cars from then and only homologate what was needed to use a gp2 engine in a gp1 car.
Amendments 7 and 17 are not in the official FIA Form of Recognition #5542 stored on the FIA Website, which goes as far as amendment 29 dated 1 Nov 1979. Neither are these amendments listed by FISA (as CSI, who determined what cars met the rules, became in 78) in the valid amendments for the transfer of the car to group A. So I wonder, do you have an earlier paper copy of the FoR? The date of the last amendment on your copy and the presence or lack of the Group-A transfer info might throw some light on it.
So, it's not clear to me what the status of these two amendments may have been or when and how long and under what circumstances they were valid. Also, I've never heard of the leave on intent to manufacture or the reduction on cars needed to re-approve options applying to Group-1. So if those amendments represent above-board approvals by the CSI they should have been fitted to 5000 cars.
I have to admit I don't understand why some amendments have FIA stamps, like 7 and 17, and others have CSI stamps. But I suspect it matters in international competitions, because (as I understand it) the autonomous CSI/FISA wrote the rules (published by FIA) and directed their scrutineering, not the FIA itself. Their role in governing international competitions being why Bernie Ecclestone and Max Mosely took on them, not the FIA, in the FISA-FOCA war of the early 80s.
The Group-2 rule change for 76 isn't very complicated. Basically the the FIA/CSI removed the 100-off rule (clause bb - Optional equipment which may be recognized with a minimum production of 100 units per year to equip 100 cars) from article 260 of Appendix J 1975 when they published appendix J 1976 in Dec 1975 (having warned the changes were coming staring in Dec. 74). You can compare Art 260 1975 with Art. 261 of 1976 (there was a numbering error with two Art. 253s in 1975) where clause cc (- Optional equipment which may be recognised without a minimum production) of 1975 simply moved up to become clause bb of 1976.
The ban was given in Art 261 1975 (for Group-2 cars) as "NB: Mechanical elements recognised in Group 2 before 31.12.75 as well as the authorised modifications according to the prescriptions of Art 260 of former Appendix J can be used until 31.12.77 for rallies. The car will be automatically transferred to Group 4."
It seemed that Vauxhall tried arguing that that this note didn't say they can "only" be used until 31.12.77, when the CSI were threatening to ban the Chevette HS in March 1978 (which they did in April) for continuing to use banned bits. But Dealer Team Vauxhall had got that car approved in 1976 (backdated to 1975) through another loophole in the ban - it missed limiting mod to "... the car for which they were approved..." So they took the Lotus 16-valve head that was approved on the Magnum and used it on the Chevette, without it ever being approved on the Chevette. I suspect that driving the Chevette through that loophole had royally p155 the CSI off. So much so that they weren't having it again in 1978, and they got Cicero in to explain exceptio probat regulam in casibus non exceptis
to DTV. It possibly didn't help that the new head of the CSI in 1978 was an ex member of the French SS (who are said not to have been very nice people) - though he only joined as a spy for the resistance, so he said.
It is interesting that it was a general ban on stuff approved under Art. 260, not just the 100-off rule, which rule had caused most complaints to the CSI as being unsporting. That meant that lots of Group-2 options needed to be re-approved, but those that had been approved under clause bb of article 260 also needed some production. This is what happened to the 16-valve head on the TR7, Group-4 mods also being covered by article 260 and a similar ban (that's what got me involved in all this in the first place), but I don't know that there were any 100-off rule mods from production standard on the Doly for 1976, etc. If there were, they would also have needed production to gain re-approval.
That production should have been 1000 cars for Group-2, but then it should have been 400 for Group-4, and the CSI accepted 50 in a number of well documented cases, notably the Chevette HSR, and the aforementioned TR7 16-valve head. There's a couple of less clear cases as well in the Porsche 944 and the re-approval and transfer of the Group-2 RS1800 into the Group-4 Escort RS on a second batch of somewhere between 50 and 58 production (BDG engined) RS1800s built in 1976/7. So, it's possible that any 100-off rule options would've been reapproved on far fewer than 1000 cars, perhaps only 50 - those cars would have to have been "meant for the normal sale" and, in the case of the 50 or 60 TR7 Sprint and the (perhaps only nearly) 400 FHC TR8 specials, those were sold-off not scrapped.