If you're running a tall deck block, I would go to a 4.375 or 4.5 crankshaft, if legal. No reason to give up cubic inches and it will reduce your RPM, which will benefit everywhere (maincaps, bearings, oiling, valvetrain, etc) Diamond will make whatever pistons you want, if you can run good fuel, 12 or 13:1 will be easy with a lightweight flat top or moderately dished piston. Managing the torque will be the primary problem, tire life is going to be horrible. I would sit down with the rule book and have a good think and then afterwards you can brainstorm with Mike Jones about a proper camshaft for good drivability. S/F....Ken M