It's kinda late now for your crank but, if I know the crank needs to be turned, I never get the work done before I get the new bearings. I will order the undersize bearings, put them in the block (no crank) and torque the mains to spec. I measure the bearing diameter in the main bore and THEN grind the crank to hit the correct clearances. I've worked with too many Pontiac motors where the crank clearance is critical and I just follow through when I build any other kind of motor. It's probably not necessary but I'm more comfortable knowing what I've got when I screw the motor together.