5 or 6 Lug -- More Confused

[gregw98]

I searched and am more confused than ever. My inline six is shot, but I have a 350/350 ready to go in my '54. So this means I have to get a different rear end. I located a 95, S-10, 4x4 diff. It is a 5 on 4.75. My new 15x8 wheels have 4 inch backspacing, which tells me by my research, that these will not fit. Plus with sticking with the front straight axle, I would want that also to be 5 on 4.75. Is there a hub and drum that would be a direct replace to a 5 lug?
Plan B
If I decide to stay with a six lug, I have a set of 15x8.5 slotted aluminum wheels. Haven't checked for clearance yet, but I am still at a dilemma of finding a different 6 lug rear end, to match my stock front.
I need some guidance on which way to go, I'm lost.