Also no experience with the 77/22H. But with. 77/22LR.
SOME will need their bolt shimmed.
I'd always recommend rechambering to Ackley or K- hornet.
Ruger barrels are a crapshoot, I'd estimate 1 in 10 are reasonable and 1 in 100 are good. (This may be a re-crown, or lapping job, or worse)
Plenty...