[Mike C]

Yes. The big block manual trans crossmember exists, and it is different. Not near as many big block manual trucks as small blocks so they can be hard to find. Not sure what all the additional parts you need are, but clutch pushrod from pedal to z bar, z bar, fram bracket etc. are all different if I remember correctly. High hump floor has different location for shifter hole as well.

I looked for a long time to find all these parts when I was going to convert my 70 Sierra Grande to manual.