That's intersting feedback and thanks for posting, but I've never encountered an internally balance Mopar engine after 1974 - in big or small block.
I've also never had any problems swapping between any of the small and big block assy's as long as I matched external and internal components. Even when I reference Allpar, there's nothing after '78 that was internally balanced - they all used cast cranks (cheaper to put weights on HB and TC than to internally balance them).
From Allpar:
Chrysler's most compact V-8 *(318) designed to be rugged and dependable - is equipped with the second-generation for 1978. Features include:
- Hydraulic valve lifter (tappets)-no periodic adjustments required
- Induction-hardened exhaust-valve seats
- Cast ductile crankshaft
- Aluminized steel exhaust and tail pipe
Again, I don't doubt what you're saying here, but my experience has been the opposite - for street applications with occassional trips to the strip.
Southernman