The Vauxhall 8v 2 litre is as powerful as a Sprint, cheap as chips and indestructible (even by me!) Although belt driven, it's a NO-contact engine. It's an easy conversion and the injection wiring is only 5 wires to running! The Omega box that matches it has hydraulic clutch and the box is short and light with a readily shorten-able shift extension.
If you want to spend money later, a guy I know of in Stafford can get 240+ bhp from one of these, but I find circa 140 is "sufficent" for a road car.
Why wouldn't you?
The advantage of using an engine that was originally fitted to the Dolomite range, is you reduce your chances of officialdom sniffing around. Personally I think the rules are stupid. I can understand them wanting to stop people rebuilding a whole car from just a vin plate but I see no problem with putting different engines in.
Also I like the idea of using a retro engine and coming from a generation bought up with computers, I am fascinated by the way old tech like the a Dolly actually manages to work. The SU carb, for example, is ingenious.
As for the piles of scrap listed on ebay, my advice is stay clear. At the very least check it turns over by hand before even considering it.
The engine in mine was such a cheap purchase and it turned out to be not so cheap. OK I got it going in the end but I had to throw a ton of parts and time at it to make it work.
In hindsight I would have been better off spending more and getting a good one in the first place.
Should have said, no danger from the 8 point rule with the Vaux 8v 2.0, it goes in the stock unaltered shell fine. As for retro, it was introduced in 1600 form in 1981, just months after Sprint production ended and had grown to it's full 2.0 fuel injected glory by 1988. I'd say that's pretty retro, but the tech is a whole generation better. Yet it's such a reliable and versatile design that versions of it are still in production now. And the block formed the basis for the legendary "Redtop" and C20LET turbo engines.
The SU carb is very clever, but it's not as reliable or fuel efficient as a Bosch Motronic!
As Alun has said, buying ANY used Sprint engine is a gamble, even a cheap one can be a waste of money with NO re-usable parts to salvage. And the cost of rebuilding one is soaring, then there are the difficulties in getting quality bearings, chain tensioners, pistons, oil pumps and so on. Even decent gaskets can be a hunt and if you intend to use it in anger, this will be an ongoing problem that will only get worse.
I can understand going to the time, trouble and expense of doing this for a tidy, solid, genuine Sprint in its original shell. Not so much on a mongrel Toledo (like mine, no offence intended Clive!)