engine opinions

Right boys and girls. The cabby is now looking good, New hood, and plans for interior BUT…. It's a 1.8 gti 8v.

Now I like the 1.8 gti, it pulls well, handles well and is reliable. So realistic views… Will I gain much with a 16v lump.
Would a mk3 gti 2.0 give it more poke.
A VR6 would be Amazing.
However, i'm a Sunday mechanic, do any of the above fit on stock engine mounts, am I talking new drive shafts, gear boxes looms etc etc etc (obviously I realise the vr6 is essential a yes to all) but a mk3 2.0?? Could I almost swap a donor car front end straight in?
is there a kit available I.e engine mounts on the market?

Also I don't want anything too new (too many electronic sensors will ruin the basic "classic" feel of the car.

Discuss!!!

Think about a 2 ltr 8 valve lump, practically a simple bolt in job, can run it on the k-jet, keep the "classic" feel but a bit more oomph, even though the figures of the 2 engines show not dissimiliar bhp. I did this nearly 20 years ago, made a nice car.