I'm glad you asked!
I purchased my kit for my 67 Coronet from Pirate Jack's. I ordered the 11" drilled and slotted rotors and added the power option. Well it was a year before I had a chance to get this installed. Everything went great and fit perfectly as far as the rotors, calipers, ball joints/spindles, lines, etc. When I got to the power booster, firewall plate and linkage, it was for 70-74 mopars and was no way going to work for my 67. So I called them and even after having this for a year, they said they would take care of it.
The guy at Pirate Jack's said in the meantime, I should maybe try the conversion without the booster, so I did. After I got everything installed and bled, I tried out the car. It stops but you really have to get on the pedal to do so. The bore is 1 1/8" which is too big for non-power and they don't offer a smaller bore. So I found out about Dr Diff and talked to Cass. What a great guy! Very helpful and knowledgable. He recommended a 15/16" or at the most 1" bore and he carries them all. He said most people prefer the 15/16" over the 1" for non power disc/drum conversions. I have yet to order because I'm not sure which one to get.
So getting back to Pirate Jack's... I ended up sending back the power portion of the kit (booster, firewall plate and linkage) and kept the master cylinder. They refunded me more than what I paid even after more than a year had gone by! It took 4 or 5 calls and e-mails to get it done, but I would have to say, they treated me good in the long run. The brake components are MBM which Dr Diff also sells so the quality is there.
To answer your question, the folks at Pirate Jack's are very nice and their kits are as good of quality as anywhere else. I would definitely recommend them. All of this took place just a few weeks ago by the way if you're wondering. Communication could be a little better, but they are very nice folks. On the other hand, after speaking with Cass at Dr Diff, I would not hesitate to purchase from them either. I think you would be safe with either company.
I've heard good things about Ram Man as well. I called but no one answered. I left a message and never got a reply. That bothers me to no end and IT HAPPENS A LOT THESE DAYS! Maybe he was just extremely busy, I don't know. Everyone seems overwhelmed these days. I can't vouch for him because I've never spoke or done business with him, but again, I do hear good things about him.
SO... I hope this helps and keep in mind, this is just my own personal dealings. I'm sure others have had different results and also have different opinions.
Now, I still have to figure out which M/C to get for my car, but I'm staying with manual brakes, that much I do know.
Good Luck and let us know what you decide to do.