Gunsmithing a Remington #4 Roller

[jnyork]

A friend has a little Remington #4 Rolling Block in .32 rimfire, has no collector value due to condition. He is thinking of getting it running as a .22 LR.

First, who is the best gunsmith you know of that could reline the barrel for him?

Second, what other factors would be involved here, such as firing pin, extractor, etc?

All information greatly appreciated.