No more than 100 USD
Try e-gunparts.com
Best left to a gunsmith
50-125 or so
Harrington and Richardson revolver chambered in 32 Smith and Wesson
10-100 usd
IIRC Cornell Publications might have an H&R book with sn.
H&R makes a 22lr 9 shot revolver, Model 904
1944
Cornell Publications has books on H&R
If it is the correct one, yes.
Mid 80s