Slant build / pistons

There are two versions of the cast crank engine.
The first generation uses narrower rod and main journals than the forged crank, but the crank itself is the same configuration and weight as the forged.
The later one , from 81-up uses a crank that is between 20 and 22 pounds lighter. The blocks used on these engines are cast thin, and are approximately 16 pounds lighter.
In my opinion, this is the golden child of all Slant Six engines.
These can be quickly identified by a 5/16s distributor hold down bolt hole vs the earlier 1/4 inch.
The rods are interchangeable between all cast crank engines.
Going with a longer rod is the exact opposite thing to do if you are looking for any low end torque. The stock 225 rod is a half inch too long already.
I would keep the pistons you already have, and just source out a set of .010 over rings, then file to fit.