Ah, this is your project

Don't use the nsg370, to low torque rating.

I will sell you my car to put that engine in + all of the eextras going with it.
Somebody put a v12 in crossfire.

There is a company that makes a single mass aluminium flywheel and adapter plate,, clutch etc to mate a BMW 6 speed trans to a mb m113 block($1,200 ish i think, cheaper then replacing with a dual mass steel fluwheel and. Kjtch), can't remember specs off my head atm, but 480bft lbs torque rating ++++, especially with the diesel trans, many in bmw swears they hold up more,, and i have seen them on places like marketplace around $500

Any ideas on your tuning ???
That is your biggest problem.