The short answer is no.
The long answer is why, or more specifically why not?
Chamber reamers do have slightly different dimensions (tolerances in machining) from maker to maker. The chamber reamer "pilots" from the bore. When a chamber is already cut this precludes the reamer from being able to "pilot" off the bore as the reamer is designed to. Instead the shoulder of the reamer is what makes first contact with the barrel. The chances of the shoulder acting as the pilot and cutting a perfectly concentric chamber are low enough that we simply feel the risk for success is too low to do this sort of work.
The other part of the equation is that when a barrel has had rounds through it fire cracking and work hardening occur. This makes the steel very hard and as a consequence very tough on the reamers, to the point that the reamer can be ruined with a single use.
We pride ourselves on doing the best work in the industry and to do less than the best work possible is just not something we want to do.