Balanced rotating assembly

Hi,

I'm building up a 383 for my 1968 Camaro. I've assembled a couple engines in the past.... claimer motors for circle track racing. This motor has a target 450 hp and a max RPM of 6000.

My plan was to have a local machine shop take care of the block work and I was going to assemble the motor. SCAT and Eagle both have "balanced" rotating assemblies.

From what I've read, those rotating assemblies can be hit and miss... people have measured the crank and rod journals to find that they are not within the desired tolerance. I've also heard that these "balanced" kits still need their balance tweaked at the machine shop.

Is it possible to assemble a motor using one of these kits? I suppose I could order the kit and measure everything before assembling. But if something does not meet the tolerances, then what? Why would they even sell pre-balanced kits if you need to get them tweaked at the machine shop.

On another note... if a machine shop gets one of these sets and the rod bearing is too large for the crank (out of tolerance), how would they even fix that?



Thanks,
Sal