273 / 318 Exhaust Manifold Question

I agree with most of the suggestions here, the important thing is to pay close attention to the advice being given. For example, if you’re going to use a 318 short block make sure it’s a 68 or 69, so you’re getting the high compression block. Once you bolt your 920 heads on it the C/R difference is minimal, and will make it better suited to modern pump gas. If you want to keep your ride height low, use your 273 manifolds or go with Dougs or TTI headers. Since you have the standard intake bolt setup, an Eddie performer would be good, an air-gap would be better (don’t forget aluminum intakes and headers will also shed weight compared to iron anything) The aluminum vs steel wheels advice is solid... I make sure to determine the weight of the aluminum wheels before buying. If you decide to home-port/gasket match anything you might as well port everything (intake to head, head ports, and exhaust manifolds. Spec your carb carefully and once you decide on your parts list check with the guys here about a cam. I believe you could go for a Comp XE268H with what you have now plus a hi-comp 318 block. 3:23’s are alright street gears, but with the build you’re doing find a 2500-2800 TC - you’ll be surprised how it wakes up a mostly stock setup.

Thanks Topless69, your comments kinda sum up all the replies to my initial questions and are very useful. I do have a good running stock 1972 318, which has an advertised 8.8:1 static compression. I was planning on using Mr Gasket 0.028” head gaskets and milling my 920 heads to achieve around 9.2:1 comp, or a little more.

I have a Comp XE262H cam, an Edelbrock Performer intake, an AVS2 650cfm carb, and a set of 1-5/8” long tube headers. If I open up the bowls & port match the heads and intake manifold, get a good multi-angle valve job, I’m hoping this will make for a way better street only combo with the 4 speed and 3.23 geared rear.

The only real issue I have is that I like the way the car sits now, so I may just port match the exhaust headers and call it a day. The Flowtech headers I have will sit too low. I may look at getting a set of Doug’s 1-5/8” headers that appear to fit better.