8 lug to 6 lug 64 GMC, also V6 to V8 swap

[64GMCpickup]

I have a 64 GMC with 8 lugs and want to convert the front drums to disc.
I am installing a 6 lug Posi rear end (I already have it).
So, I need to install matching 6 lug discs in the front. Can I obtain parts from a newer model for a bolt on conversion? I would like to keep it as a 3/4 ton truck.
On another topic, are there bolt on mounts available for swapping the 305 V6 to a 350 V8? I would like to install the V8 and 700 R4 (I already have them).
Any thoughts you guys may have on this would be gratefully appreciated.
Thanks,
Steve