I had some Suntour 9000 downtube shifters that were theoretically designed to work with normal spaced 7 speed freewheels but I could never get them to be smooth across all cogs. A Suntour freewheel should be fine.

My Suntour Sprint front (7s friction)derailleur requires trimming when going beyond 3 cogs. I can't find a way around that. But don't give up on that bike. It is a beauty. But looking down at those bars I'd never use would bug me. I rode my son's 89 with a complete 600 group the other day and I was very impressed even with not so nice Rubino Pros. If his paint was as nice as yours, I would adopt it and find another bike for him.