If H&R makes one for it, yes.
I would not do it if it is choked more than Modified.
$50-$150, depending on condition.
Harrington & Richardson (H&R) the maker of the Topper shotgun, was located in Worcester Mass.
To replace the firing pin in an H&R Topper shotgun, first ensure the firearm is unloaded and safe to handle. Remove the barrel by unscrewing it from the receiver, then locate the firing pin inside the bolt assembly. Use a punch or small tool to carefully drive out the old firing pin, and then insert the new firing pin in its place, ensuring it is seated correctly. Reassemble the shotgun by reattaching the barrel and performing a function check.
Comparison to others with known dates.
Check old gun catalogs
Topper is a brand name of a line of basic single-shot shotguns made by Harrington & Richardson. H&R is owned by Marlin Firearms Company.
The H&R topper model 490 JR was made from 1961-1983.I hope that you find this informative.
Between $50-100, depending on condition.
Blue Book of Gun Values can help
Yo Ho and a Barrel of Rum