I'd make sure the engine was as good as possible, by getting the head serviced, the valve seats checked, new single valve springs ($20 for a set of 1600 VW springs), plus the best carby you can find. The new repro carby's aren't much good, but there are plenty of cheap 32/36 DGV's on Ebay. 1200's & 120Y's aren't that slow with a good stock engine, it's just they're all worn out. As for the bottom end, if it's got even compression, I'd leave it be. It's all pretty tonka down there, but a new water pump, oil pump & a new electronic distributor would help it stay healthy. A new rocker cover gasket so it doesn't cover everything with oil would be good, too. The 'bomb' car bashes always seem to have things breaking down, but that's probably how they edit the show. Always need a bit of drama, & comedy, too. A 120Y is light enough to fly over most surfaces, also. Use a Japanese rear end, a H145 because the Borg Warner alternative has a reputation of being weak. Get the 13 inch wheels with larger tyres, make sure the brakes work (can't go without stopping), then get ready for Hero status as the guy in the 120Y.