Questions regarding transfer of hand guns and more...

My brother-in-law (BIL) or his father (now deceased) purchased two hand guns in the early to mid-eighties when they lived in NJ. I assume the guns were purchased in NJ as they were NJ residents at that time. They owned and ran an Italian Deli. Since then my BIL moved to FL and has since moved to PA. I should add that I live in PA also.

Shortly after he moved to PA he asked if I was interested in having either of these pistols. My wife had no problem with us having a pistol in the house. I chose the Walther PPK/S. …Actually he gave it to my wife - his sister, and she gave it to me. I have had a PA license to carry since that time. I carry the Walther everywhere except the office.

I asked my BIL about State or Federal registration of the pistol. He said he doesn't know and has no paper work.

Is not having the pistol 'registered' an issue/problem ?
If it is, should I get it registered, and if yes how ?
Is there a way to check if it is registered ?
Or should I keep it as a stay at home pistol beside the shot gun and get a new carry pistol ?

Thanks all