273 rings available?
Kanter used to make pistons. There may be another manufacturer or two out there if you dig deep enough. My machinist was impressed at the quality and consistancy of the EGGE's. As far as rods, the 273 rods are the same stout rods and the 318 uses and will hold up to 400+ horsepower. Most every rod manufacturer makes a rod for the small block Mopar If you think the stock ones won't handle the power. You could use 340 rods but have to add weight to balance.
