Nuts went .060 over bore on a 77 Motor home 400 still plenty of meat the shop told me can go up too a .100 over bore the 72 400 NA cold block only had more Nickle built same way as the later ones just has less rust on them after a shot peen ..
Holley carb don't you hate when all that gas spills out during a jet or valve change right on ur clean engine ... if its hot God forbid better have a fire extinguisher handy..