Dan I've used these before and you can run a reasonable sized cam and still have adequate piston to valve clearance. If your going to build a fire breathing 318 with a wild cam then cough up the extra couple of hundred for the KB167s. Flycutting valve relifs in them is also an option as Oldmanmopar said - the crown is plenty thick enough. You asked specifically about off the shelf non Forged pistons - std replacement rebuilder pistons, the speed pros or the KBs are your options.
That's because there are more of them - it's a bigger market. Still enough parts available to build a high HP small block mopar available - just have a look around this site, plenty of stout motors here.