Rod bearing size

[Rob1]

Hello, im rebuilding my 1989 turbo supra, its torn down to nothing but the block and the crank because im not replacing the mail bearings or turning the crank because there was no damage to any of the bottom end i just had to replace the pistons due to a dropped valve.

My question is since im using the factory rods, and factory crank how do i tell what size bearings to use?

I talked to a mechanic friend of mine who worked for toyota when the MK3 supras came out and he said it has something to do with the six numbers stamped on the block and the numbers stamped on each rod but its been fifteen years since he worked there and he cant remember what the formula is or what numbers need to be added together to find out bearing size.

Any one have any idea how to get this info?