Spoke Size / Spoke Length Database - What size spokes do I need?

A friend has a 2006 Langster that he's dropped a couple of spokes on - going to rebuild the rear for him with the stock hub and rim but I was hoping to order the spokes ASAP as I won't be able to get my hands on the wheel to measure it until the weekend.

Anyone happen to know the required spoke length? (32H 3-cross AFAIK.)

I think the rims are Alex DA16 (ERD 535.3mm according to the internets) so if anyone just knows the rear hub dimensions that would do me...

Thanks

^That's an MTB rim ERD. Deep V are 582mm and H Plus Son 557mm.