What newer models black leather seats will fit a 70-74 Challenger.
Im looking for something more comfortable and with higher side bolsters.
Any ideas?

Fit is one thing, looking like they belong is quite another! Most late model seats are just too bulky to look right. Good luck. Time to cruise the wrecking yards.

I put some Honda S2000 seats in my Cuda, very nice pro-touring look and fit well

Can you post some pics?
What was required to make them fit?

Years back there was a board member Reflections7, or something like that. He had a convertible Challenger that had seats from an Omni/GLH or similar car. They fit well and looked decent too. I think the key is what ever seat you put in, have the back seat custom upholstered with matching pattern. I think that will help tie them to the car a bit more.

I had Omni seats in a Dakota. Omni was a cheap car and so were the seats!! They look fine but that's about it. I'd say its only been in the last 10 years that companies have upped their game in the seat department. Besides, finding decent seats as old as an Omni could be a real challenge. That's a 25 year old car now! When I had them in my Dakota, Omni's were still a relatively new car.

If I can figure out how to do so on here.
I had to weld up some simple brackets to locate the seats properly.

I put Mazda Miata seats in my Cuda, very happy with the look and feel, simply made an adaptor bracket to bolt the Cuda runners to the seat, raised the front 1" and the back 2" and perfect for my 5'10

I used seats from a Dodge Calibre in a truck, I quite like them. Take a trip to a junk yard and have a look through some cars and see what you like.

I put SRT-4 seats in the Dakota, they are very comfortable. Maybe Viper seats would work? I agree with recovering the back seat to match.

I always enjoyed Reflections7 posts

I installed the 1970 Challenger optional seat covers as supplied by Legendary. Could not be more pleased.

When I did my seats I covered the old ones and built up bolsters on the edges bottom and sides. I would think any shop that recovers seats could do it and using the original seats saves customs mounts having to be made.