I guess you want an equalizer hose from SCBA to SCUBA. I don't know what brand SCBA you use, but it might be impossible to find a stock item that meets your needs. We have used them in the past, but since neither Draeger or Scott make them, we had to have them custom made. They really are not very practical because of the volume/pressure differences. The SCBA bottles we use are 65 cu. ft.@ 4500psi, so you couldn't completely fill a 80 cu. ft. SCUBA tank unless you are using a cascade system. Going the other way, you wouldn't have the pressure to fill a SCBA bottle from a SCUBA tank. The best you can do is get the tanks to equalize if you are transfilling.
Your best bet would be to get a ready made SCUBA whip, and have a hydraulic shop add the proprietary SCBA filler and guage and relief valve.
Doug,