Iron 273 4 barrel manifolds

I like that intake and run them on the street. No track time and no quarter mile time. We used to have a quarter mile marked off so we would know if changes helped or hurt. A friend dynoed a 2 barrel pistoned 273 with an Isky E-4 cam and the rest of the Commando good parts including that intake. It made 265 hp. I also run Jet Hot coated factory exhaust manifolds with the Commando 2 1/4 single straight thru exhaust.

Given the 2 barrel pistons were 8.8 to 1 deck height changes as well as how much is taken off the head and head gasket thickness that motor could easily be in the 9 to 9.5 to 1 CR range. Was the dyno pull pull done with 920 heads?