What offset size rim will I need to use on a 4/6 drop

[sduckworth13]

I have read so many different combos, I'm now lost in what works great. What offset should I use if I want a 4/6 drop on my 1967 GMC 3/4. I have suspension from a 1974 Chevy 1/2 ton donor truck, I'm installing a 5 lug disc/drum setup. I'm doing a almost complete swap of the frontend except the crossmember and I'm going to use the rearend out of the 1974 Chevy 1/2 ton truck also. What drop kit gives the best ride and is a reasonably price kit. I know that the 1974 suspension is wider in front and back. What would be the best offset to use with 20 inch rims or 22 inch rims?