i got 2 5.3 laying around in the garage and the one on my motor i was wondering if a 4.00" crank will fit in it with no problem and if i could bore it out to a 4.00"(6.0) with no problem and i want a cam to go with it but somethng that will make it work like crazy got some stage 3 heads to go with it from texas speed

 

Max bore is going to be much less. Try 3.898" for starters, probably 3.905 maximum before you're at minimum wall thickness. You can successfully make a 383 out of your 5.3L with that 4" crank. Have a machine shop sonic test the block(s) before boring over. I ended up being at minimum wall thickness on two of the cylinders after boring to just 3.898".