radius block

[cheapimitation]

Hi

I recently de-fretted and slot-filled (with CA glue and ebony dust) my 6 string bass, and am now ready to re-surface the fingerboard. My q: I have found radius blocks in a few sizes, in terms of length and width; the 3" wide block is available in larger lengths (8" and up), while I have found a 4" wide block, but only in a 5" length. My board is 3 3/8" wide at the heel, and has a 15" radius; I'm planning to change that to a 16" radius, because of the ready availability of tools with that spec. Would I be better off with the shorter but wider block, or is it ok to use the 3" wide block and move it around at the high end of the board to cover the entire surface? I realize it might be possible to use either tool, but am wondering what would be the best bet for someone who has never done this job before.

Thanks