I'm looking at a small block Chevy engine. Without taking the valve covers off and obtaining the foundry cast number in the rocker arm valley, is there any way to determine what kind of cylinder heads are on the block? I can tell you that there are no accessory bolt holes on the heads, and the cylinder head production cast marks show a narrow rectangle with a small triangle in the middle above it. Are these heads to a 283, 327....high perf or just passenger...etc??