Any question answered...

Has to be 40? You can get 48 wheels from BLB, not quite otp as they build to order.

You can get loads of bmx hubs with 48hole as well as blb hubs... And velocity deep v's, chuckers and a few other rims come in 48.

I think easier to source in the uk than 40.

i've got the rim sitting here waiting to be built to something
it has to be 40 as i don't feel comfortable drilling the extra 8 holes in the rim myself