To my knowledge, domed pistons were never used in these engines as a factory piece, they are all flat top. I do know that domed pistons existed in the aftermarket, though. They pop up from time to time on Ebay.
Personally, I would suggest gong back to a stock type piston, my preference being TRW forged, just like the factory pistons were. Sealed Power pistons (with their rings) would also be a good choice. If you want a little extra compression, milling the head will bump it up a bit.
