kody,
Read Perklo's Handi rifle trigger job in the FAQ's. After you get the pins, and parts out for the trigger job, it's just one more pin to remove to replace the firing pin. Be careful, you don't lose the firing pin spring when you remove the firing pin assembly. While you have everything out, you might as well do a trigger job.
After that take a look in the firing pin hole, and make sure that there aren't any burrs, or a small sliver of metal inside the firing pin hole, from the original broken firing pin, before installing a new firing pin. IIRC some of the firing pins made by H&R weren't heat treated properly which led to some firing pin breakages.
It's also possible the original owner of the Huntsman practiced dry firing
without a
used primer in place to catch the firing pin strike. That may have led to the original firing pin breakage.
Best of luck with your repair. Let us know how you make out.