hey bull, save your money.
I had the same idea several years ago. what a waste of time and money.
Though the idea is just grand, the reality was really disappointing for me. I could not find any 9mm round that would shoot worth a darn (FMJs, HPs, JSPs, RNLs, etc) ie: large groups, lots of flyers, key-holes. etc. The .355 bullet in the .357 bore isn't a good match I guess. This specimen was a rather good shooter with .38 and .357 BTW.
Besides, the New Model Blackhawk has the same cylinder indexing set-up as the Vaquero you had, ie: the chamber doesn't line up with the notch in the frame when it clicks. IIRC, you didn't like that much and were looking at a New Vaquero with the Colt-style system instead.
Just my opinion though, feel free to get it and suffer the same frustration...
You might want to try the .45 Colt/.45 ACP Blackhawk instead. Both calibers shoot well in my experience.
edited to add:
The Old Model Blackhawk (the earliest were the Flat-Top models) lacked the transfer bar, had the 3 screw frame, etc. Discontinued in '73?
the New Model Blackhawk has the 2 pin frame, has the transfer bar and has the same internals as a fixed sight Vaquero.
The New Vaquero has the smaller frame of the original Flat-top Blackhawk, but has the Colt style indexing, etc. The 50th Anniversary Blackhawk is like a New Vaquero in frame size, lockup and cylinder indexing, but has adj. sights.