I don't mean to be contrary, but too much is made of this neutral bouyancy stuff. Being vintage like Capt'n, in the "era" you didn't have all the choices we are presented with today. Most of us used 72s, or double 72s. 38s were around, but not common. Later 42s (bumped up the pressure from 1800 to 2250) and then 50s made the scene. So you had to learn to dive with what you had. And, there was no BC so you had to estimate weighting. If you were a bit negative, swim. Positive, pick up a rock. In fact, at Brownstain, I was light most of the first dive (grabbed the wrong weight belt), but made a real nice rock my dive buddy. Sure I could have stopped the dive, went back to shore, etc., but for the couple of pounds a rock was fine.
Find a nice set of whatever, learn their characteristics and enjoy the dives. To me, condition of the vintage tanks you purchase is more important than bouyancy stuff. This will be learned and appreciated.
If you are looking for something that makes the modern LDS happy try one of these sets. Double 50s and 45s.