I'm with Slick on this one. Turboing an old engine with a collection of parts from various cars around is too much like hard work!
As for the comment about just turning up the boost on a turbo! This is a receipe for a meltdown. With a modern fuel management system the turbo is governed by the management. if you put a bleed valve on like the RST's or R5T's used back in the 80's/90's to turn up their boost you're making the management take a back seat at running the engine. More boost means more fuel to compensate. If this isn't carefully managed then you melt pistons.
If you seriously want to turbo a 16v then you'll need to replace the pistons, con rods, possibley the crank to adjust the compression ratio. Stacking gaskets is a bodge and should be avoided. do it properly from the start! 300bhp is a lot of power to ask from a 1.8 block and given than the KR block isn't as braced as the 1.8T's found in the newer cars I wouldnt want to risk it myself!
Why does everyone think BAM coded 1.8T engines are the be all and end all of the engine code game?! BAM isn't the best and it isn't the easiest to install.