I have completely gotten out of my element and purchased a 69 Plymouth Roadrunner. Just an itch I have always wanted to scratch!
It seems that the only 3 companies I can find that make PT suspensions for it are, RMS (Alter-k-Tion), XV motorsports, and Hotchkis. I fully realize there are not nearly as many available products as there are for a Chevrolet, but I wanted to make sure that I did not leave anyone out of my search.
I hope this will help. I will start with what in my opion is the worst system out there. Magnum Force. This system uses your stock shock mounts and this will cause the inner fenders to move in and close the hood gap. If not keeping the hood from opening. There are plenty of guys you can find on the web that have had and removed these.
Now XV. looks like a very good system. The only down side I can think of is it takes alot of work to install. This would be my second choice.
RMS (Alterkation), I am a little partial to this system. I own one. This system is a complete bolt in system. Very easy to install and lots of adjustment. You can find plenty of very fast and highend cars using this. Most of the Mopars on the Powertour that have a aftermarket suspenion came from RMS. This is just my two cents.
A stock type system like Hotchkis is very capable.
The fabbed K-members show a lot of extra benefit to someone doing motor swaps in an smaller A-body like a big block or a modern Gen3 hemi. Even a Gen3 Hemi in B-body (Road Runner) my be an issue with a stock K-member, beyond just motor mount adapters.