DT Frank would agree about the cars sitting. He has been trying to get one for us to play with. We are still working on that.
Did some measuring on 2 heads yesterday. One was an old Keith Black P4120711 head sold thru Mopar and the other is an Indy SR. Ports, rockers and lower 4 head bolts are equal spaced. Only things I found off were the push rod holes and the stud that screws into the bottom of the intake port. As you stated they are 1 and 5 same and 3 and 7 matched. I understand why the push rod holes are off due to the offset on cam lobes due to the cam bearing journals being between I guess. But can't see any reason why the studs odd spaced unless it is because the boss on the block for the stud to go thru had to be relocated for push rod clearance but the are only moved sideways about .020. wouldn't think that would take relocating the stud.
Side note. The P4120711 heads were some a buddy from KC saw on Craigslist a while back in ATL and called to get me to look at them and buy them if they looked good. Spares for a nostalgia FC he is building. I bought them and will deliver them on my next trip out west. They were metal stamped JENTZEN'S and BARNETT RACE CARS. Had to be pre 1986 I think because I think that is when Barnett left Norcross for downtown. Don't know where Buddy Jentzen went after that. Also had 1282 stamped which could be Dec 1982.
Frank asked how fast you have gone with the old 10.5 car and the PS car. I showed him the video of the flying boxcar and he loved it. Said "Now thats a ride".