Roller Rockers 1.5 vs 1.6

DentalDart said
How do you decide on which ratio to get?

I didnt get any when I purchased my aluminum heads but now SM has all the SS rockers in stock ( well kinda...) so since they haven't had any in 7 months I think I may pick up a set... I kinda want 1.6 for a little "extra" lift from my cam but worry about valves hitting pistons?

Build...
30 over 340, pistons all around .012 out of the block
Xe268h camshaft
SM CNC fully assembled heads (pictured)

I know I know buy the expensive ones that are "better..."

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With 0.012 out of the bore you want to watch quench clearance. Probably looking at a compressed head gasket of 0.050" thickness.
For a 0.030 over 340 with 2.02 intake valves, cam LCA for best performance should be 104.6°. A 106° LCA and 1.6 rockers should work well. What is important is the overlap triangle. The high lift rockers snap the valve open quicker, increasing low lift flow during the critical overlap "cycle". This could require retarding the cam 1° or 2°. That aids V-P clearance.