Yes, it is ETA case you can tell by the crownguards. And it is BP serial so... your watch is either late BP or GMF:) (people say GMF is made in 100% of BP parts)
Early BP had awful bezel insert, yours is much nicer so it's GMF or recently updated BP, I can't tell more.
The most important thing is that watch is period correct: clasp+rehaut+dial, that does not happen often in reps.
I think you did a good deal, this watch is better than Noob v7, I love the crystal - it's superior over the v7.
Personally I wouldn't touch it, watch looks nice oob and you can't improve eta case anyhow.
What do you want to mod? BP case is not gen spec.