Someone out there needs to make an adapter kit for this deal! Seems like it would be relatively simple for somone who has the means to manufacture a machined steel plate. So instead of using the OE part and drilling and machining the opening, you buy the new plate, go to the junkyard, dealer or parts store to get the rest of the stuff and you're in business. All Mopar too!
BUT, as stated above, nothing wrong with properly working drum brakes. Many of those same 90s Cherokees were still using drum brakes. Disc brakes are not light either...