im looking at 2 speed pro forged piston choices.

SB-Chevy: 350
Stock type piston with 4-valve reliefs and pressed pin. Compression ratios:
9.72:1 w/std. stroke & rods, 64cc head
8.62:1 w/std. stroke & rods, 76cc head

or....

SB-Chevy: 350
Flat Top, 2 Valve Reliefs, Press Fit or Floating Pin. Compression Ratio:

58cc Heads: 10.79:1
64cc Heads: 10.06:1
68cc Heads: 9.75:1
72cc Heads: 9.24:1
76cc Heads: 8.99:1

which would be best? is the bottom one worth the extra $10 a piston? these will be flogged with a 150 shot of nitrous. they will be put on a set of scat 5.7 i beam rods.

I personally like the idea of 2 valve notches, becase the notch can be a stress riser, although you can avoid this by smoothing the edges. As far as CR goes, this can be made up by a thicker head gasket. However, your best quench/CR may dictate the 4-valve piston. Usually I try to get the best quench and CR first, then go from there.

I like the floating pins makes assembly and dissasembly much easier most shops charge 50 to press fit a set of 8.

my rods are are press rods. after some research the less expensive ones are heavier at 610 grams!!!! vs 495 of the more expensive but the lighter ones use 1/16 rings. so im not sure now.

Please double check and see if the compression heights are the same ...

pdq67

PS., and the old heavy, 4-notch pistons have been ran as cast pistons in million's of 350's stock...