[Unreal]

Sounds like you are not looking for the "stock" look, so why not fab a block off plate, and eliminate the evap box? Then sell the b/b evap for $400-500, and buy a Vintage Air system.

BTW, I have a 69 b/b with a/c and stock exhaust manifolds. There's one spot where I have about 1/2" clearance between the evap box and the manifold.

 

[Unreal]

The "small block crossmember" that's being referred to is for the s/b with Muncie, PG or TH350. The "big block crossmember" is the one for b/b muncie only. Since the TH400 was only used behind the b/b, there is no s/b version.

The b/b muncie crossmember allows for the fact that the b/b is moved to the pass side, to allow clearance for the steering box on the driver side. I was not aware of any relocation fore or aft, but it may do that, also, but I doubt it as the driveshaft is the same for s/b 4 speed and b/b 4 speed. Not sure about the length of the driveshaft with the TH400.