Early 340 pistons had 2 valve reliefs and stuck a little above the deck. 72-73 had flat tops with 4 valve reliefs that were .080 below the deck or so. Those pistons pictured are aftermarket. Measure and see if they come close to deck level or stick way below deck. They look like some pistons I put in one of my 340s. About 9.5:1 w open chambered heads or closer to 10:1 with some closed chambered heads.
the chamfer around the piston is in the hole (cannot really get a good measurement becuse of the chamfer) but across the center/top of the piston is at deck or out some. i will try to measure it tonight.
