Wheel size/opinions?

[cbbeard]

So this is the 84 Stepside I am rebuilding with my son, and we are getting closer to finishing, which is good since he turns 16 within a month. Next on the list is new wheels and tires. We are thinking that Cragar Smoothies (with the baby moon hubcaps) are the way to go since we are kind of giving it a throwback look with older GMC badges and the like.

The question is in regards to size. Should we go with 15x8's all the way around? Should we go with 15X10s on the back? Should we consider another size? FYI the wheels on it now are 16X9ish.

Also, what size tires would look good with this setup?

Any and all opinions are welcome and wanted!