Another vote for the USD Royal Aquamaster or Phoenix Royal Aquamaster.
The first stage internals are the same as the Conshelf so maintenance is not an issue. It is a balanced first stage like the modern single hose regs out there today. Fit it with a Teflon HP seat and the new silicone valves that are currently available and silicone hoses on the way and you will have a real winner. There is nothing you can do with a single hose that you can't do with one of these, including NITROX. I'm not a technical diver and I haven't seen much talk about it but, I don't know why you could not do some technical diving with one of the Phoenix conversions either. After all, Cousteau went down 200 or 300 feet to the Brittanic with an unbalanced single stage double hose in the '60's. Others may know something in this regard that I don't. If you do a search for Royal Aquamaster you will find many who feel the same about this regulator.
BTW, Luis H who responded earlier is an engineer and developed the Phoenix nozzle. 3 LP ports and 3 HP ports. You can hook up your octopus, BC, Dry suit, SPG, whatever. You can't go wrong if you were to get one and if you don't like it there are plenty around who would take it off your hands. (It breathes a little differently from a single hose but, you will like it. There is a slight learning curve regarding proper positioning lower on the back and clearing the mouthpiece and exhaust hose.) It is a great modification to a great regulator, and you can't go wrong with it, IMHO. YMMV.