But why not take a decent 'project' 8v GTi and tweak it. The engine's pretty good, but might benefit (as one of mine did) from a Weber Starchip - which gave an increase in power of about 12%. (Too costly?) The spheres could be changed for 16v ones couln't they? And what about roll bar?
I did consider this as a project once - using a TZi estate and 'sporting it up'.
I think this is more a point of interest really - because the question why bother? comes to mind.
Depend on the cost... Donor car: £150. Spheres bar bushes etc. £250? Ph 1 body kit - maybe another ton if you can find some, etc. Then you've got to paint the creation. Could end up with a nicely turned out GTi for less than the cost of a decent 16v. Easier to live with day to day maybe?
Just a thought!