Itīs al about money isnīt it ?
For a turbo set up on a M30 engine, you really don' t need to upgrade to forged pistons. It' s important that all bearings, pistonrings front and rear seals are in good shape. Your' re gonna rebuild it so that should be no issue. I completely agree with BJL on the cam issue. A faster cam in a turbo set up would only kill the performance unless you should use a cam with a higher inlet lift, but with limited duration. Stronger headbolts is a very good suggestion. The headgasket could be replaced by a race spec one with normal thickness. 9:1 comp is really enough to reach 280-290 at the crank with a intercooled set up.
Be sure to ge the right info on torque settings for the headstruts and bearing bolts.


Good luck and have fun soon.