Rod length versus piston compression height

If I de-stroke the motor, i need a longer rod to put the piston back up to stock. In that case, I don't think the piston would strike anything.

340: stock stroke 3.310/1.655 (50%) 339.44 cubic inches
305: custom stroke 2.96/1.48 (50%) 303.55 cubic inches
305: custom stroke 2.94/1.47 (50%) 301.50 cubic inches

340: stock block deck height 9.6
340: stock piston above deck .018
340: stock connecting rod length 6.123

305: custom connecting rod length 6.25 (0.127 > than stock)
340: stock piston compression height 1.840
305: custom piston compression height 2.00 (0.16 > than stock)


340: stock rod length (6.123) + stock compression height (1.840) + 50% of stock stroke (1.6550) = 9.618
9.618 - 9.6 stock deck height = 0.018 piston above deck (factory spec)

305: custom rod length (6.25) + custom compression height (2.00) + 50% of stroke 1.48/1.47 = 9.730/9.720
9.730/9.720 - 9.6 deck height = 0.13/0.12 piston above deck

alternate combo #1: custom rod length (6.25) + stock compression height (1.840) + 50% of stroke 1.48/1.47 = 9.57/9.56
9.57 (9.57 - 9.6 deck height = 0.03 piston below deck)
9.56 (9.56 - 9.6 deck height = 0.04 piston below deck)

alternate combo #2: stock rod length (6.123) + custom compression height (2.00) + 50% of stroke 1.48/1.47 = 9.603/9.593
9.603 (9.603 - 9.6 deck height = 0.003 piston above deck
9.593 (9.593 - 9.6 deck height = 0.007 piston below deck