Not sure if I titled this correctly, I am looking at both a 350 +.030 rotating assembly and a 383 rotating assembly with identical parts other than the stroke on the crank. Scat 9000 crank, H-beam rods, probe forged -12.5 cc dished pistons, new harmonic balancer, new heavy duty flex plate, rings and bearings completely balanced. I think I will use a Dart shp head, regardless. When I run the numbers on Comp-cams software (8-407-8 .. 252/258 .472/.480) I get .5 hp loss and 30 #/ft of torque gain for the 383 over the 350. When I run DD I get the same HP loss, but only about 25 #/ft of torque gain. I know that I am horsepower limited by my cam choice, but I want low end torque, the engine will rarely see rpm's north of 3500. What I did discover using my DCR calculator is that with a .045 quench setting, and 64cc combustion chamber I go from 9.4:1 SCR to 10.1:1 SCR. That's way more than I want. I can lower the CR by going with the 72cc combustion chamber version of the Dart shp heads, which puts my SCR back to 9.4:1. Is there a noticeable performance difference between the two sizes of combustion chamber if I maintain the same SCR? I thought that maybe I could use a bigger intake runner so I ran the numbers with 180 and 200 CC intakes, and it moves my curves up the RPM range, but doesn't seem to affect the total power any. Given that I am after dead reliable over power, does it make sense to even go to the 383? I know that this discussion has been beat up, but mostly for guys that want all out power. If I was after that, I would use a different cam, bigger heads, and go 383, but that's not what I want. Also, would I give up mpg with the 383 over the 350? I am building this motor for my alaska trip next summer, and will be towing a 22-24 foot travel trailer. I know I won't get great mileage with that much weight behind me, but after the trip, I will drive this truck daily.