If I can fuss a bigger pushrod diameter in there I will. The ports rule in that area and the pushrods take what's left. We already run .015 brass sleeves as pushrod tubes, and we get pretty close...there is some offset opportunity, but the rules call for unmodified lifters. Can't run 460's due to
oil hole orientation.
Between a 1.77 and a 2" the answer is less than 10 HP. Possibly 5 or less. Same was true for the now illegal little mains. It may be the right thing to do (after all finding 5 HP in ten places gets to be a pretty nice number) but I can't afford to do it this time so the question is moot.
I need to focus my limited resources on things with bigger returns on investment - - heads and cams.