The crack between action and side safety is a common one on Greeners; not a cause for alarm, but keep an eye on it. That and the forend piece dropping out make me think it could do with a little TLC and epoxy. What does it weigh? Facile Princeps Greeners could be very light for a 12. Yours is numbered about 1000 before mine.
Personally, even with nitro re-proof, I'd be sticking with BP.
Has he got any more to sell?!
I've a soft spot for the Beretta 410E too; I inherited my grandfather's, bought new in 1951 with the part proceeds of a wool boom wool cheque; I wish the gun it replaced was still around though...
RG