273, could it be a commando and CAM question?

have you done a compression test yet, that might give you an idea. I had a 273 that was a commando and whoever rebuilt it put in stock pistons, only had about 110psi on all cylinders - and mine had a bigger cam in it also. Needless to say - it now has a 360 in it and the 273 is probably going to the scrap yard. Would think with the 10.5 pistons you should get over 140 anyway.