You done good!
Offered the same rifle for that money, I'd have ripped the butt out of my jeans whipping out my wallet.
MANY prestigious and highly-regarded gunsmiths have rebarreled Garands to 7.62 over the years. The barrels they used will not show the markings we have come to accept as "normal" (for a MILITARY rifle).
The quality of the "build" seems evident. I think that, not only did you buy a truly fine rifle, but you did the right thing by an older gentleman who needed the proceeds from his rifle.
Although I'm "sorta" reluctant to say this, if you're having second thoughts I will gladly pay you the same amount you have in the rifle to get it. That's how strongly I think that you did very well indeed.