273 4bbl dyno results

Great info. Is your 273 a Commando ie. 10.5:1 compression and dual point distributor? The factory specs on the Commando/Charger rated 235HP with solid lifters. Where do you think the HP gain came from on your engine? The OPEN headers are probably the biggest help. However, I don't think headers are a big HP gain over the stock Commando exhaust manifolds/exhaust system when either one is run through legal mufflers and all the plumbing. I would love to see what the dyno reads with stock manifolds with open exhaust or the headers choked down with mufflers. I'll bet there is not a nickel's worth of difference between the 2. Chrysler thought so too with the 273 Commando and larger single exhaust. 340 and up is a different story. If Porsche could get 235 BHP out of a 2.7 liter, 2v, single exhaust engine in a 1973, stock 911S; we should be able to get 391.66667 BHP from a 4.5 liter Commando V8.
Just got a 67 Formula S, 4sp with a monster 340, 2x4bbl. I want to go back original with a stock Commando 273 with the refinements required to get close to 275HP on pump gas and stock hi-po exhaust system. Reckon blueprinting, porting and polishing would get me there? Thanx y'all for your expertise.