the 43mm is God's own lens, no doubt. it's The reason to own the Mamiya 7 system, really. Fantastically sharp into the deepest corners of the negs, it's as good as wide angle gets on medium format, bar none.
BTW the viewfinder on the 7 and 7II are essentially identical the 7II has a polarizing film on it, but other than that, no difference. I have both, and in practical terms they are interchangable.
The meter is the same between both 7 and 7II, contrary to what was implied above.
Yes, the external viewfinder is a bit of a hassle but for what you are using it for it won't be a big issue at all. Even in normal use it's pretty quick to deal with it that way.
Definitely worth getting the 7 and 43mm combo!