Trick Flow 270 heads are max wedge size and use a standard rocker arm. They are an extended runner design so the intake is moved up a bit from stock. Works fine but you'll need a solid valley plate.

Have the machine shop figure out the piston selection. It will depend on what clearance they want to run and what ring size is available. If it is only a thou or two then you can order the pistons a couple of thou oversize and use file fit rings and it should work fine. Without knowing any numbers we're just guessing at an answer so have the machine shop figure it out.