handspun is run out of QBP .. there are other places to hire wheels assembled for you

OP wants a weight target as a priority.. good luck with that.

Sew up rims weigh less than clinchers..
Im sure there are weight weenie hubs , aluminum axles & such ..
maybe a large flange hub because the steel spokes are shorter, reduces the overall weight.
Ceramic bearings probably weigh less than steel ones.. etc..
Titanium spokes used to be made and sold.. now? IDK.

I dont own a Scale..