Progun, yeppers that's a 1980 serial number.
I got my first FFL in 1978 and i clearly recall that in the early 1980s there were some customized 3" models floating around. I firmly believe that gave S&W the kick in the a$$ needed for them to produce some themselves.
If I had that gun I'd definitely spend the $30 to get a factory letter for it.
That would show where it was originally shipped and what the original barrel length was.
I forgot to ask earlier about the rollmarks on the barrel.
If there are any I'll wager they're closer to the muzzle end and not centered.
I've searched for years for a Genuine Lew Horton 25-3 but have never even seen one much less found one for sale. Of course I'm sure that if one were found it would be much more than I could ever afford. The going prices for my 3" Horton 29 have become obscene.
I did find a genuine S&W 3" model 57 at a local gunshow about five years ago.
It was new in box and the seller wanted $450 for it. (I even have a witness.)
During the 15 minutes it took be to get back from the ATM it was gone.
Now according to the real experts, a 3" blued Model 57 doesn't exist.
But I had it in my sweatly hands, and it was real.
So, somewhere in western Washington, somebody has
MY gun.
If your 25-2 is like the other .45 & .44 conversions I have seen, the action will be icy mountain road slick.
And of course the balance is a close second only to a 5" short lug N-frame with target stocks.