Forged pistons of the type you're looking for (pop-up for the 10.5 compression) can be had from a number of aftermarket companies such as Ross, Diamond, J E and Venolia.
Couple of questions here;
1. Are you sure you want 10.5:1 compresion? If you're boring your engine at all, and will likely have the block decked and the heads resufaced, with all that cutting, you could end up with 11:1 compression if you buy OEM-configured "pop-up's" with the little dome on top, as the original Comandos had.
That's probably too much compression for pump gas... even 93 octane. Early Mopar combustion chambers aren't very forgiving of low octane... and 93 octane is low compared to what these engines were designed for.
2. Are you going to use forced induction, nitrous oxide, or run it 7,000+ rpm?
If you answered "no" to all of those questions, why not use a flat top, hypereutectic or cast piston? Much cheaper, priobably lighter, and easier to find.
3. If you're going to bore this engine, buy new pistons and rings, and have it balanced (good idea with replacement pistons), have the rods rebuilt, and a valve job, you're probably going to end up spending as much or more money as you'd spend putting a 360 Magnum crate motor in the car, which would give you hydraulic roller tappets, and a TON more power. It's virtually a bolt-in. You'd have to get an intake manifold, but I think nearly everything else will fit (accessories, etc.)
It's visually very similar to a 273 and the tranny bolts up, if it's an automatic. Dunno about the sticks.
Lots less work and probably less money if you get the 320HP version. No ZDDP worries about a flat-tappet cam going "flat" and more power than you would realize out of a 273 unless it were built pretty radical....
Food for thought....
Bill, in Conway, Arkansas
