Impossible to answer without a detailed description of all markings.
Early Harrington & Richardson revolvers did not HAVE model numbers, but model NAMES. In your case, the model name is "22 Special".
H&R made thousands of revolvers.
IIRC Cornell Publications might have an H&R book with sn.
I also have one of these pistols. Have you had any responses off line to your inquiry?
50-125 or so
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
H&R makes a 22lr 9 shot revolver, Model 904