I think Rocks are a little slimmer than most. At least my #2 seems to be.
In 7mm, I'd go with a #3 and keep it under 23" with a modest shank. A Brux 3 with .25-.5" shank and 22" would be a nice in a lightish' handle. Flute it if you don't like weight forward.
That's exactly what I did with my last 7MM-08, #3 Brux with a .75" shank/fluted & finished at 22.5". Balances really nice in a Classic Edge.
