I prefer the Japanese Bess to the Italian over the Italian. I know many say the Italian is better, but the craftsmanship just seems finer to me. the bulb on the stock is nicely pronounced, the barrel is rather thin, but probable not an issue. The lock is probably the biggest difference for me. the springs seemed chunky, and the pan was pretty shallow compared to the Italian, but you don't need that much powder anyway.
it it's in good condition, I'd say go for it, you woun't regret it.
I wish I could find a good Japanese Bess cheap.