> I think you should not have any problem in installing system 7 on SE/30, 
> it runs properly also with 7.5.3.

Be careful. 7.5.3 was buggy. 7.5.5 was much better (it actually fixed more
bugs than it created).

I'd vote for 7.0.1 or 7.1. The former's still free, and 7.5 was a heavier
operating system than 7.0 or 7.1. If you're doing mostly NetBSD stuff, get
a quick OS; not 7.5. :-)

Take care,

Bill