So far as I know, the only candidate in an H&R would be the discontinued 7.62x39 with it's .311" bore.
Tim
Tim, I think you may be confusing the calibers. I believe the bigger Russian is actually a .308 caliber. However, many, if not most, of the Nagant rifles have oversized bores. It's not unusual for them to be .310-312.
The .303 British would be a good re-chamber for the 7.62X39, with it's .311 bore. Without looking at the cartridge dimentions, I would think the .30-30 would be ok for the big Russian. Frankly, It would probably be the only rifle chambered for the 7.62x54 that would actually be in .308.

Hmm ... I never checked, but does NEF bore the .30-30 to .307 or .308? That would make a difference in considering the 7.62x54.
A thousand pardens if I'm incorrect.

Joe