Pacific Tool and Gauge are great to deal with but they will only rent reamers within the U.S. I live in Canada and have not been able to rent a reamer from the many American reamer renter companies, I have to buy each one. Many guys buy the reamer, do the job they need done and then sell the reamer for close to original cost online.
I have not had any success chamber reaming with a boring bar, but if you polished well it might work. Also for this straight case, a chucking reamer should work and they are far cheaper than purpose chamber reamers.