You'd probably only loose a 1/16" of barrel. That's enough for the Ackley reamer to "clean-up" the original chamber.You have to have a Smith recut the chamber and set back the threads. It's not that hard for a gunsmith to do. Pricing depends on the gunsmith, but you are going to loose about 1/2 an inch off of your barrel.
You'd probably only loose a 1/16" of barrel. That's enough for the Ackley reamer to "clean-up" the original chamber.
Your only getting 3050 fps with the 55 gr ballistic tip in your 243 and 3175 in your 6mm-284??It is a personal decision. If you have lots of money and time plus the cool factor intrigues you, then do it. My feelings are don't do it to this barrel.
It shoots now doesn't it? How many rounds have gone through the barrel? Why not wait till you wear out the barrel?
Besides gunsmithing, there are additional costs: best to use virgin brass for fireforming, and you will need custom dies.
My 24" 243 got 3050 fps with the 55 gr ballistic tip and Varget. I have a 6mm-284 which is a bit larger than the 243 AI and it got the 55 gr bullet to 3175 fps so what are you expecting to gain?