Good afternoon guys....i purchased a cheap 331 block  100 bucks..i wanted the street master intake that was on it and i need a set of good 390 rods.
it has the large beam rods..casting C6
Got he deep sump baffled pan and pickup
Bore is std 3.875
i though maybe i could use the block for  std 390 also
i cannot get a 1/4" Allen wrench between any cylinder..But i noticed the block was sleeved. They sleeves are approx .125 wall
would this be safe for a over bore to 4.050? or even 4"
how much overbore can i get out of a sleeved block ?
I can use the help
Thank you
1952