TTS,
'Red' Lyles at Colonial has worked on barrels for me for years now. I can't reliably recall how many forcing cones he has extended and choke tubes he has installed for me and for friends who wanted that work done. I have absolutely no complaints with anything they have ever done for me and would recommend the company for any barrel work you need. They are 'home town' folks for me, I was born in Selma, AL.
Talk to them first, if you haven't already. Sometimes there are problems with barrels not having enough metal in the barrel walls for RemChokes to be installed and they may have to use a 'thin wall' system. If you have the equipment to measure barrel wall thickness (a dial caliper etc) that might help figure things out.
lpl/nc