Here's a couple of ideas:
Early 90's Mustang seats are near bolt-in, so I've heard. I've heard same for Escort seats.
Pontiac Fiero, and some Volvo buckets have speakers built into the headrests. These are supposed to be easy to fit up to the CJ brackets, and make a convenient way to hear your tunes when the top is off.
A buddy of mine just installed some Pontiac Grand-Am leather buckets in his '79 CJ7, about 3 weeks ago. Again, he said it was easy. I think he needed a flat piece of steel to bolt to the seat, then bolt to the CJ bracket. Flat steel is available at any Tractor Supply, Home Depot, etc. He gave $75 for the pair of leather buckets at a local boneyard.