I'd go with 80mm as the first lens. That's what I did. It's about 39mm equivalent in 35mm.
But if you prefer wider angle, then 65mm (32mm equiv.) first, then 150mm (71mm equiv.)?
That said, telephoto lenses for Mamiya 7 have quite long minimum focus distance and I don't see myself using them often. I only rent for weekend at discounted rate from a local shop when I need them.
If you are planning on expanding into the wider lenses, you might consider the 80.
On the other hand: I never ever (well hardly ever) use the 80mm lens. I almost always use the 65mm lens. It is almost at the point that I am questioning why I own it. Almost.
I have ordered a 65mm, I am a wide user really, I use my 15mm Heliar about as much as my 35mm, so the 65mm really suits me more than the 80mm. At the moment, I'm planning/hoping for the Mamiya to be a one-lens setup, but we'll see.