Iv'e been in this situation a few times and looking back i realise that on many occassion i should have stayed with what i had in the first place and finished it.What i actually did was go through a period of having one "unfinished project" after another and not feeling too good about it.
If you can have the mk2 as well and get it to how you really want it and then transfer then that may be a good way to go but if you ca'nt,ask yourself if you can really see it through and that it wo'nt turn into another unfinished one when you see something else you like.

I'm in this situation now.I saw a 16v going cheap but it needed a lot of work.I sold my 8v to my mate accross the road with the condition that i would take all my modded stuff off the 8v and fit it to the 16v.It's been going on 6 weeks now and every day i look accross the road at my old car and think "why did i bother,should have stuck with what i had".No going back now though !.