80’s 318 compression ratio figuring out where I’m at.

Whole balance job involves:

• Weight matching the pistons & pins to each other
• Rings and pin locks, if used, are weighed
  
• Then weigh the rods to find the 'small end weights' and the 'big end weights'; this takes a special weighing jig
• Then the small end and big end weights are matched to each other.
• The above processes can take some labor time, which is where a lot of cost is for the whole balance
• The next step is to take the final numbers from the above steps, and compute what is called a bobweight
• Weights, called bobweights, of the above computed value, are fastened to the crank journals, the crank is spun in a special machine, and the crank and bobweights are balanced.

If you are doing a true performance build, you'd prefer to do all the above. If you are doing a cruiser build or need to cut corners, like in the case of putting in KB167's in a 318, and you just need to get back to factory quality balance, then:

• The KB pistons come closely wight matched out of the box, and the pins, rings, and locks (if used) have very small variations that you can live with for this. You just weigh a couple of pistons, a couple of pins, and a couple of ring packs and use those weights for the bobweight computation.
  
• The rods have some variation in weights but weighing the small and big end is the most complex part, so for cheap, you just live with the variations, and use the nominal small end and big end weights for the bobweight computation.
  
• You use the numbers from above and compute the bobweight, and hand that and the crank to the shop to balance. That is as good a process as the factory process.