I was surprised to find valve reliefs in the pistons from an engine of this era.A '74? Good thing you aren't trying to save those pistons then...I think the compression ratio on the mid 70s "Smog Dogs" was like 8:1...good for 20+psi of boost....but not for anything else.
I’m thinking they may not be original. The heads have “289” cast into the valve area. My buddy says this engine was pulled from a ‘66 coupe. I need to take a look at the piston I removed so far for any markings. I removed it with a length of tubing and a BFH. I may need an air hammer to get the rest.
I’m thinking it was a V8 conversion that it was pulled from. No other way to account for the hodgepodge of parts.