I'm also in the process of converting my Coronet from column-auto to four speed. I went with the American Powertrain kit. I started the installation but have not finished it so no drive report yet.
Couple observations thus far;
The AP kit comes with floating spacer and two different length stud/slider things which position the TOB on the input shaft relative to the clutch fingers. Based on my measurements with the parts I'm using, the spacer puts the bearing too far forward. Their solution is to remove the 2' O clock retainer bolt and replace it with the longer stud/slider thing then shim the bearing until it's in the right spot. Seems reasonable enough but generally you would not have this issue if you used a mechanical clutch fork.
Also, I'm not sure yet how I'm going to deal with the master cylinder actuating rod. The OE clutch pedal has a flanged pin to retain the clutch rod so if you wanted to utilize the OE clutch rod position, that pin will have to be drilled out (for a shouldered bolt) to be able to get the rod end eyelet on it. You could just drill a new hole somewhere else on the pedal but that may affect the pedal ratio. Come to think of it, I may have an old clutch rod somewhere, maybe I can lop one of the ends off and cut some threads into it so it can be screwed into the rod coupler. Then I won't have to drill the pin out of the pedal.
The kit comes with a firewall bracket to mount the master cylinder. Unfortunately it's a universal part so it's not a perfect fit. If you want to use the OE clutch rod hole, the bracket does not fit over the hole very well and consequently you can't use all four bolts to secure it. It's probably OK but just leaves a little to be desired for the price of the kit. If you're handy with a mill you could definitely come up with something a little better.
Last tidbit - The kit also comes with a plastic L bracket to mount the master cylinder reservoir remotely. If you decide to use that, then you have to 1) find a place for it relatively close to the master, 2) likely will need to drill two holes somewhere on your firewall and 3) you would now have a modern, white plastic reservoir on your firewall that looks out of place. However, it looks like there should be enough room to mount the reservoir directly on the master so I'm going to try and make that work.
Those aren't negatives per-se, just things to be aware of which you might not know until you were into the install. Would be nice if there was a "Mopar-specific" kit that makes better use of the OE parts, especially the clutch rod and firewall hole pieces.
BTW I drove a car (Mazdaspeed 3) with a 'performance' hydraulically-actuated clutch for 140K miles, it was smooth and easy. To compare, shifting my '76 D100 4 speed on long trips would wear me out.
