Right, change of plan for this thread. I'm now turning it into a road rally car. The plan is to restore the shell with an acid bath and an electro-playing to protect against rust, poly bush bushings, Gaz gas coil overs, LSD, hydraulic disk rear conversion, 2 pot front calliper conversion, spitfire steel wheels widened to 13x7.5, and then I'm going to build the engine up with a hotter cam, billet internals, removing of mechanisms that can leach power like fuel, water, and oil pump, getting a low resistance alternator from a more modern car. Followed by exhaust, halogen conversion, and a full interior and rear seatbelts
If you're going to keep the 1500 engine, and I know there will be mockery in one or two quarters for even considering it, here is my two pennorth.
First of all you don't need to go mad with pistons and rods in this long stroke engine, the crank is the weak spot, get it cross drilled and tuftrided and get everything balanced. Keep the mechanical oil pump, it's too much trouble to mess with it and uprated ones are available. The other pumps, ditch if you must, but the gains are tiny. Port and flow the head, convert the seats for unleaded and 3 angle seats. A good 4 branch is vital (and will cost you, the Spitfire one doesn't fit a Dolomite) then I would go with Megajolt and Megasquirt using 2.5PI throttle bodies. Stir in a decent cam and you MIGHT, if you've done it right, get 120 bhp Finally, add lightness, it's the best and cheapest way to make a car faster!
All this will cost you a fair wedge and probably not get you to standard Sprint output - but it's your car, you can do what you like and at least it will be different!