6 or 7sp freewheel with 9 or 10sp derailleur?

You might need to use a touring or MTB rear derailleur with a rear cassette of that size. IIRC a lot of short-cage models handle up to 28t.

That was actually the plan. Shimano say most of their MTB long cage (SGS) derailleurs are good for 34T rear. I wasn´t even looking at roadie stuff. Have to see what sort of small sprocket chainset I can turn up. I may not need to step up to a 34t rear.