Re:
I assume this is for the C Record build discussed in another thread?
The only reason to go 7-speed is if you're going Syncro. Personally I'd avoid it. I had it running quite nicely with a 7-speed Regina America freewheel but it was still not very satisfying to use.
For friction, I'd go 6-speed. There are loads more blocks out there to choose from and as the cogs are a bit wider spaced, they are less fiddly to use.
I'm sure others will know which particular ones are best, but I've got a couple of Regina Extra blocks that are excellent. No fancy profiled teeth, a little bit agricultural, but a good satisfying gear change and no annoying tinkling noises.