340 High Compression Pistons

And the Ross pistons have a negative deck height in a standard LA block (CH = 1.804"), so the OP may not be at the point of any problems with the decking. With and 020" decking, the Ross pistons will be approximately .002" out of the deck, so that is not all that bad. Put in .040" Cometics or .039" Felpro's and see if the piston heads can be machined to fit the X chambers. I guess that is still custom in a way but he is close and not $1500.