I think for a mk4 conversion you will need a analogue loom. It's definitely worth getting a full car if you can. It's surprising all the little extra bits you will need, throttle cable,air filter box and more.
I've joined up on some of the puma forums, that can be helpful.
if you pm me your email i will send you some very useful info i got from zsoc before it closed.

ah yes the cambelt, i paid a mobile mechanic to come and do it, guess i won't know for sure until I've got it running. He's turned it over by hand and checked it but said he'll come back and check it again once its running.

not sure about spacers, mine is totally standard apart from the engine and front brakes so couldn't really say.