SRP makes a piston specifically to fit the chambers in these heads...about 13:1 if I remember correctly....ran that setup on a 355 in my Datsun, badass set of heads....a bit outdated, but still make horsepower with the right combo.
I saw 540hp at 7800 IIRC...with a 650HP Holley on a Vic Jr. and a stupid big solid roller.....680 lift lift and 306@.050 or something like that.