I take it you are refering to .577 2 3/4 BPE ?

From the info I have the Gibbs Farquharson is .985 Major 14 Tpi ?

A Ruger #1 is 1" major 16 Tpi

If the barrel is modern steels then IMO it should not be a problem.

If however you are going up to .577 NE I would have the action magnafluxed and/or x-rayed first.

Regards