First...my machinist is not a fan of KB pistons and cites an abnormally high failure rate compared to other makes. He did not like the weight either but at 728g they are less than 10g heavier than the stock '68-71 piston, and they are forged. My only other option besides KB were all in the 6-700 dollar range and that was not gonna happen. I chose what would work for my budget. The old pistons (L2322F) were 660g and 12.5:1...which was simply no longer an option for a street motor on pump gas.
Second...why am I not "listening to my builder"? He's on board with the .030 over pistons I've chosen along with the '69 forged crank, and has *suggested* a preference for Eagle SIR-I forged rods over reconditioning the stock forged rods...which makes sense. This should provide me with a very solid and strong bottom end IMHO.
This project is to be a solid street runner and will likely never be raced, or only to establish an ET baseline. But more likely not. Stock 340's are known to be hard, fast revvers...why should this be any different? I would rather lose a few seconds in ET than have a piston come apart or break a ring. At my age, I intend this to be the last time I will have the bottom end out of this engine.
The heads are the next item up in the batter's box, because the cam choice has to be based partially on compression and head flow...hence my question about the 1.88 valves. I have a set of 2.02 X-heads I could run on this thing but they've had no work done to them as the J's have previously. My question was not to start a range war, just to determine whether my builder was correct in stating that "for my intended purpose (street runner) the 1.88's will create more usable torque down low (6000 and below)". The time to do head work, porting and valve changes is now; before I select a cam or valve train. Also, I would like to note that while he does many, many engines yearly, he's not necessarily a Mopar guy, and moreso not necessarily a smallblock Mopar guy...(this in no way reflects anything bad on his part)...which is why I turned to the forum here; to get the answers from guys that build them and know them.
I'm not going bracket racing. I'm not gonna lose money if I run a half a second slower. I'm not running for 'pink slips'...I just want a car that starts easy and runs strong and will make me feel like a punk kid again when I wail on it.
Hope that clears the waters for some of you...and thanks for all the advice to date.