Are your KB191s set for 0 deck, or set to the KB .011" down in the bore? The dome is .150 tall, but I'm referring to the actual top of the piston at teh edge... If you are set at 0 deck, and run the 373s, that raised pad will come up about .085". If you run std Felpros at .043", that's getting very close to your chamber roof where that step comes up. especially if the heads were milled at all. IMO, the flat tops are the way to go if you're at 0 deck now. However they may give you a nasty drop in power when runnign the same cam. You may want to address that. If they are .011" or so down in the hole (or lower) the quench domes are a good option. However, depending on your cam, you may still be too high for pump fuel and an open chamber. And when running the quench domes, you will have to check every cylinder for piston to head clearance. Do not assume they all stop at the same distance away from the head. You want .040" or so and if you need to polish the chambers to get a flat surface, do it. I am curently building a 440 with the step head pistons. It's a royal PITA to get things where they need to be to work right. I plan to polish the chambers, then mill the head to get my perfect quench distance. I also am running a cam that will bleed off pressure low down. So the final deal will be an 87 octane gas 10.8:1 iron headed engine. KB-silvolite has a good dynamic pressure calculator. plug in your cam and see what the various pistons do for you. You want dynamic compression ratio to be below 8.5:1 for a hevy street geared car, no higher than 8.75:1 for pump fuel and better gearing or light weight.
