Hi 55.., welcome...!
All your current parts are good.
Your post is a bit vague. What experience do you have..? What RU going to do with this rig..? Where RU..?
"I would like a four speed"
WHY..? It's a bit of mod work & (IMHO) serves little purpose in a 4x4 road/off road rig.
Get the #'s & letters off the trannie..., The tag is on the pass. side.
351 is fine except for some cooling issues from time to time.
302 will likely give you all the engine you will ever need.
Give up as much info. as you can, even if you think it's unnecessary. This will allow much better help
from our members. (& rid of a whole lot of guessing)