When I purchased this new from the Chevy dealership I purchased the 1970 LS6 454 short block (without the rectangular port heads). I was originally planning on using it for 100 yd. sand drags. So I went with oval port heads which were street ported and supposedly the valves were changed to 2.19 intake and 1.88 exhaust.

Erik are those Brodix 270 cc ovals aluminum or iron? I am leaning toward oval port heads because my new air gap manifold is for oval ports and I am not using the brand new open plenum Torker II. Once the heads are removed I will know for sure exactly what I have and probably will have to go with hardened seats.