I think '69 up rods from a 318 are the same as 340 rods, and same as 360; except some are bushed and some are not.
My 400hp 367/4-speed, has bushed 318 rods in it and a rebalance for KB 107 pistons. It's been been to 7000 plus, many a time.
When I put my engine together in '99, I had at least one or more sets of every SMB factory rods available. Those 273 rods looked like spaghetti next to the others and
I just couldn't see those 4500 rpm/180hp/low-torque rods, going the distance.
