If the spoke hole pattern at the hub is symmetrical,(online pics aren't clear/big enough), and if you intend to do a radial lace, then one spoke length should suffice. If spoke hole pattern at hub is grouped, then you may need/want different spoke lengths.
At magnification, it looks like the outermost spokes of two groups are closer together than the spokes within the group.
I really can't advise. I've done a few radial fronts with unmatched spoke counts rim/hub by leaving empty holes in the hub, and for those one spoke length have been sufficient. But I've never skipped more than one hole at a time, and I don't know how the offset of that would compare to your offset.
Unless you're dead set on ordering rim and spokes at the same time, get the rim first, then measure. Tape new rim next to old, measure the differences in length for where the spokes would be going. with a bit of thought, this can even tell you which lengths to order.
Whether or not to do it is a so-so issue. There would be a slight change in spoke alignment, which is generally frowned upon. I've had no issues with worse, so I'd charge right ahead. YMMV though.
There's a bit of work/risk regarding figuring out which spoke lengths to use. If you're looking to use "boutique" spokes, either be certain about having the lengths figured out, or be ready to accept the money spent in vain on wrong spoke lengths.
Nice rim + nice spokes may take you well towards an new wheel, with no hassles and no inherent risks.
Last edited by dabac; 10-18-11 at 05:20 AM.