VERY important question about a BBC in a '56 pickup

[jds319]

Here's my conundrum...

My 1956 chevy was clipped in 1997, adding a 1979 Trans Am / Z28 front end. we then test fit everything with the motor and tranny we intended to install: a 454 bbc and a 4 speed muncie. Here's the catch: we didn't test fit it with exhaust manifolds / headers on the motor. Now, I'm seeing people modifying their motor mounts and firewalls to get such a powertrain to fit.

So here's my question: will I be able to find headers / exhaust manifolds that fit my motor and front end without having to modify my motor mounts and firewall?

Help! This problem could set the project back even longer!