Here's a place that can do the work you need.
1013 South Michael Rd
St.Marys PA 15857
his name is Nathan. I know him, and he does good work for a reasonable price. Shipping is quick and communication excellent.
As for the regulator. I have a stock Phantom that is set up for use with a regulator. I use an old "Ergo" Autococker reg. It's an inexpensive and dependable reg.
There are going to be a wide range of opinions on this but I use this gun a lot at scenarios. I've used it for years this way. It works for me, and there is nothing different about the internals on this Phantom than you would find on any right out of the box guns.
Stock springs. TPC turned in about 4 turns. The guage runs at 625 - 650 psi. The gun chronos at 280 - 285. Takes me about 30 seconds at the chronos. I love it. Nothing worse than the looks I get when I get in line at the chronos for a big game with a pump!!!
But then to have them watch me crank out 3 consistent shots, get my tag punched and out to the field in under 30 seconds...........priceless!
That said, this is only good for CO2 on 60 plus degree days. It works with HPA, but not as well. My guage is a mini HP guage from Palmers. These are good gauges, but a paintball gun guage is not exactly a precision instrument. I feel that it is close to being right, becasue I can crank it up to the tank pressure, and the guage reflects the change.
Your guage might read a little different, and there are a lot of people that claim a Phantom can't run at these pressures............what can I say........works for me???
I love this set up................