Re: airtronic + hydrotronic combo??
A D2 will keep you toasty in your RB, especially without a top. When I installed my D2 I simply T'd into the fuel line. Granted, this was an IDI and not a PSD so the setups and fuel line sizes could be different. I know it is recommended to have a separate suction line, but I had no problems with mine.
What is your primary use for the Hydronic? Primarily for a block heater, or for hot water? There are likely some cheaper ways to get hot water if your use is minimal.
2009 Express AWD, CCV Top & 50-ish home build. Daily driver/camper/kid hauler