Piston and rod bearings installation

As above.... once the caps and rods are mixed, they HAVE to be sorted out or reconditioned. They are machined together and if mixed the cap will not match up rigth to the rod and the bearings will be sieze to the crank when tightened.

I am trying to think of a good way to do this. I would try to:
- Take one rod and try each cap on it one at a time (torque it down with the bolts each time) and see of there is a ANY 'step' in either 'matchline' where the caps meet the rod on the inside of the assembly where the bearings set. ANY step, even .001" means you do not have a match.
- For the first rod, go through all 8 caps and find the one that matches exactly. Set that aside as one assembly and then start the same over and over with each successive rod.
- You should find and exact match for each one.

The problem above is finding a way to measure precisely any 'step' at the matchline of each rod assembly. You can feel a step of .001 to .002" with your fingernail but I am not usre that is good enough. A dial indicator would be good but many do not have that. Maybe someone has a good idea on how to make the measurement.