there are 2 ways to do it. 1 cheap (unstable engine) you hahe a kr engine and put 2 gaskets on it; and keep original pistons, you look for home made parts,etc... wil give power. but you wo'nt do much miles. cost. around 200-2500€ (i'm from belgium)
2 the expesive way. (long life) you could build a 16vg60 with the basic engine from the kr; but the pistons and rods from an audi S2. (you only need 4 of the 5) :) you fit a metal G60 gasket. and the block is ready. for real safety. you better let the engine balanced... Than you schould come on the standard 210/220ps. with a relyeble engine... now you can get tuning started. reworked G. with small pulley. real hardcore is 60mm. :) and head P&P original kr cams do great on 16vg60. so only changed whan you want to go hardcore racing... when everything is done right. with flowed G-lader. wit 68mm pulley, and ported and polished head. you easy get 240/250ps. without pushing the engine tot the limit.. with small pulley, cams en bigger valves. you could get JD engineering power of 330+ps. but this is what i call hardcore. and stupid to tune a 16v g60 for this kind of money... put the same money in a S 3 Engine. and you get 400+ps. jd style....
Parts that are hard to find (for a god price) are;
rod's and pistons. i sell them 1000€ cheaper then the dealers here...
Rocco intake manifold.
G-lader
You better put in or golf g60 (non airco) or rallye intercooler.. they are expensive...
and a good read good price conversion kit....
If u need parts. i know the way to them. :) cheaper as the shops. but they are still expensive....
as wrote before. you also need bigger brakes to stop the power. my favorite option the brembo's with 305x28 disks. stopping great.
and you need also or a g60 gearbox. or a tdi gearbox. 16V is way to short for this kind of power....
also think about the suspension..
After all you would not build a great car, with a great engine. to crash it the first time you drive around the corner...
need more info contact me.