I do have the 50n, 65, 90, 110, 140macro,150, 180, 250mm and some self-modified micro and tilt lenses. All Mamiya RZ glass is great. You will also find the RZII much easier to focus than the 645AF.
i use an Ixpress 96c and 132C with HV adapter and a self modified leaf RZ to HV plate. It works great, no shimming or focus recalibration was needed. I have now bought a mamiya RZ ixpress adapter to try multishot on the RZ( i'm not sur if that wil work because of all the moving parts between shots but it will be worth to try.
Go for the latest versions of the 50 and 65mm lenses, they are perfect.tele you already have, maybe a 140 macro or better the 150mm wich is wonderfull for portraiture.
best regards, Raf