I'll second that, springs are very hard to drill. I drilled holes in my modified spring pack to move the axle one inch forward, it was tuff to do! I think that the space in between the U-bolts is dead, meaning it has no movement and no or little stress so hopefully it will be O.K., I don't know forsure yet sine the thing is still "a work" in progress.
Althow I do think messing with the main leaf is VERY sketchy, and you need to think it out completely! If you do not have a military wrap (two loops around the front spring eye) Then if the main leaf brakes, YOU WOULD HAVE NOTHING HOLDING THE AXLE IN PLACE!!!!.
Twiztid- I know I just contridicted myself, but thats what I know about this.