Put the BB back in the frame and install the crankset. Measure the distance between the chainring and chainstay. Muliply that distance by 2 and subtract 8mm(4mm each side) then get a symmetrical BB that much shorter than the current BB. Or you could just find out the correct BB length for that praticular crankset and get that size.

Edit: measure the distance between crankarm where the pedal mounts and the chainstay,not the chainring.