Silvertop head doesn't fit without work as far as I know.

The 1.8mm gasket in combination with the blacktop head and ST170 bottom end gives the compression ratio.

Clutch I have no idea, pretty sure you will need a custom flywheel to go with the ST170 6 Speed box, I have seen a good few people say the ratios in that box aint the best for a turbo car, also it is a lot of money to put a LSD into it.

Management would better if it could be programmed, unless you go to MSD for a chip for the current ecu.