lets see how good you are: exhaust manifolds

[judgeyoung]

OK, I've got a weird one for those of you with a lot of extra parts to look at. I am going to run a 350 buick in a roundy round car for the torque and light weight. Rules call for cast iron exhaust manifolds... but they don't say the "original" exhaust manifolds. From pictures it looks like the exhaust pattern is similar on 350's and 455's. I'm sure that the inner passages are much bigger on the 455.
What I'd like to do sneaky is to machine an adapter plate that would allow me to bolt the 455 manifolds (or anything else you know is similar and good flowing) to the 350 heads. Is there any chance the port spacing is anywhere close. If this won't go, what other ideas do you closet "cheaters" have to give me an edge. Intake manifold years, casting numbers and modifications would help too. Lets get creative here guys, the tech folks don't know a buick from a maytag!

[theoldguy]

The 455 exhaust manifolds are longer. I don't think you will be able to mate them to your 350 withoutsome really odd ball llooking adapters. They would catch that even if they are not too sharp on Buicks. There are probably some 350 manifolds that flow better than others, but I don't know which is which.

[awake13]

Don't know about manifolds but its flow you are after regardless , how about blasting and powdercoating the insides of the manifold. Of coarse your already going to port them... Ian

[judgeyoung]

I think that I may try to carefully saw a section out of the engine side of the manifold to allow access to do some porting, then braze it back in place. Anyone have any experience here?