The bbls are metric length in cm as already stated. The chokes are probably marked under the forend wood denoted with a series of stars/asterisks. I forget now how they go but I think 1 star is Cyl, 2 is Imp Cyl, 3 is Mod and 4 stars/asterisks is Full.
The 440 doesn't bring all that much $$,,they are a decent field gun. But for SC I don't know if they'd hold up to the # of rounds you'd be shooting if you really get into the sport.
All depends on how deep you intend to get into the sport.
I shoot it quite a lot with nothing but elderly pumps and SxS's,,an occasional semiauto thrown in. All fixed choke and all but one is Full. But I just shoot for grins and could care less about a plastic trophy at the end of the season.
The older guns do break down now and again, but I fix my own so I don't see it as a problem. If you don't,,you want something that can stand up to 10's of 1000's of rounds w/o a worry. Repairs can be expensive and not worth it on an inexpensive gun to keep it going on the torture test run that continuous clay target shooting like SC's can be.