Small block on 6 cylinder mounts?

[rjeiii]

I have a 68 c10 that I have a 350/700R combo, Is there enough fire wall clearance to run 6 cylinder mounts? I have both forward V8 mounts and the rear 6 cylinder mounts. Would prefer to run the 6 mounts to clear the headers I bought. Is there enough room to run a HEI Distributer with the 6 mounts. We used the same mounts on my sons 66 c10 (6 cylinder) and worked great with a small block, but we had to modify the firewall when he put in a big block. I would appreciate any input you guys have. Thanks john