Cross drilling axles. Any info appreciated.

I just bought a second frontend for the 61 f100 to rebuild, clean-up ect. I'd like to cross drill the axle and have it powder coated.
So, what would be the largest hole, and how many is still considered safe? The truck has a 390/C6, so the axle is carrying alot of weight. The truck is being built w/ "gasser/ street freek" styling so I have removed the bumper, inner fenders and battery in the bed ect. to lighten up the front as much as possible. Thanks for any input, Graham

 

try this *** http://www.jalopyjournal.com/forum/showthread.php?t=23306&highlight=holesaw

 

Another archive link:

http://www.jalopyjournal.com/forum/showthread.php?t=192038&highlight=drilled+axle