One question about your picture Slonda. Where did you get those hoses for your vintage reg? They look like they came off a megalodon rebreather.
Those are new production silicone hoses from Vintage Double Hose available in black, yellow, green, gray. As well, www.vintagescubasupply often has some nice neoprene hoses. These hoses are generally 1.0X1.5 which is the standard for USD/Voit double hose regulators.
I never really had much difficulty then or now maintaining good buoyancy control and a proper horizontal position. The difficulties of vintage are often exaggerated
