A stock 305 is going to be a bit of a dog compared to a good 4.0L. Of course, if it doesn't stay stock,...
The 305's not a bad engine. It's not a performance engine, but there's nothing wrong with it. It has the standard SBC engineering and will hold up pretty well.
If you have a late '70s/early '80s motor, check the factory compression specs. Most of the V-8(all makes) lost a ton of HP in the '70s due to lowering compression. The 304 in my CJ had 7:1 and change.I couldn't believe how much the machine shop knocked off the heads to bring it up to 9:1.
TB injection isn't well understood because it didn't hang around long enough to get a big following. Work's pretty good though.
The TH350 will hold up fine in an XJ. That won't even need built.
Good luck, 'should be a fun project.