Not neccesarily. I'd use a surface plate for this because I have a small one. I'd place the cemented pair flat on the plate, if both surfaces were convex I'd make a ring and lap it flat/parralel. Use the V-blocks against the edges to keep everything centered, and give the balsam a few weeks at least to set. Personally I'm hesitant to use UV curing cement, it's much more difficult to decement the lenses.
I recemented a R-R on an old Kodak folding camera using balsam from local trees. The camera was my mother's father's, I now have pictures of her taken with that same camera over a span of almost 80 years.