thanks for all the useful information guys.
i planned on using the original drivetrain, and ive kept every part of the bike except the saddle. i am in the process of ordering parts for the bike. found some 6003 bearings, but i don't know what kind of spindle it is suppose to use. can i use any sugino one? bmx spindle maybe?

also...would a better option be to go with a threadless bb?