8&3/4" mopar vs Phord 9" vs xploder 8.8" rear

The 8.8 is fine, and parts are dirt cheap. But you will need to fabricate. E-brake is easy as they are pulled with cables, you may need new cables or fab up a bracket or two, plus the perches. Otherwise it's a solid choice.
But... I'd use the 8 3/4. $800 is fair money if it's been completely gone thru and ready to bolt in. When I buy a used rear, its a used rear. If it's got stock parts but new gears, it's a used rear and about 100% cheaper than building one of your own but you'll have to hunt to find one with new axles and big bolt pattern. So look around. You should be able to find a solid casing and backing plates for under $200. I see them fairly regularly. Buy a chuck or build one, order new axles and bearings, replace the brakes, and stick it all together. I think the Ford rear is the cheapest option, but only because you have to fab and my time's worth something. The C body deal you can cut down, then you have brakes and everything. That might be the cheapest mopar option assuming you get usabl parts in it. Then you pay for shortening and axles but the intial buy, plus the axles and cutting will be more than the 8.8.