DO NOT REUSE SPOKES!!!! You can reuse rims.
The hub diameter designed for a disc brake is probably larger than the hub you now have, This automatically means you have to replace the spokes.
There is no standard hub and wheel configuartion. There are differences in the number of spokes --from 12 all the way up tp 48-- there are hi-flange hubs and low flange hubs and some in between. Then there is spoke lacing --radial, cross one, cross two, cross three or cross four. Each of these configurations require a different spoke length.
The point is, your spokes probably wouldn't work anyway even if it were safe. Being thrifty is a good thing, but not if it will be unsafe.
Most shop I know of charge about $25. to build a wheel but only about $10. to true one.
Have n ocomment on your last question.
Last edited by ljbike; 05-07-02 at 03:37 PM.