I'm still going to go with 1430P. There is a Bundy 1430 that has just the Selmer USA stamp, which I just lost the link on; sorry
(but you can see this one).
Here's another where the seller doesn't mention Bundy. There's an
83xxx horn listed on ebay where the seller calls it a 1430P.
Here's a 1430P with no stamp at all.
Opinions ahead:
* Your horn has the satin, not shiny, finish. That's relatively new. I'd say post 2000ish, but I don't generally look for bass clarinets, so I could be plus or minus a few years.
* I think that I remember hearing that the "scalloped" keys (i.e. for xxx|xxx) are post 1990.
* If I was going to sell the horn, I'd put "1430 / 1430P" in the ad or contact conn-selmer.com and get a definitive model name and year manufactured. Remember that "Selmer USA," i.e. Conn-Selmer, and "Selmer Paris" are two different companies.
I have never seen a Selmer USA serial number chart for bass clarinets. Saxophones, up to a point (and possibly still do), followed the Buescher serial number chart. Note that harmony clarinets, which are generally alto clarinet and bass clarinet, tend to follow a serial number chart that's different from the Bb soprano, i.e. "regular clarinet," serial number chart.
I like the cosmetic condition of the horn. If you intend to play it, I'd take it in to your local music store and see how much you'd have to spend to get it in perfect mechanical shape. If you're planning on selling, you'd probably just want playing shape.