small block heads, 4027596 casting # any good??

This is what they can do according to Hughes Engines:
Stealth-ported" S/B oval track heads '596' casting number OEM valves 1.88-1.60

Stealth Valves 2.02-1.60



OEM Stealth CFM OEM Stealth CFM
INT INT Change Exh Exh Change
.100" 66 71 +5 51 80 +29
.200" 89 144 +55 103 124 +21
.300" 136 192 +56 131 149 +18
.350" 176 211 +35 136 156 +20
.400" 184 226 +42 140 160 +20
.450" 186 231 +45 142 168 +26
.500" 184 223 +39 141 168 +27
.550" 183 218 +35 142 168 +26


Note: These flow figures are representative of improvements
that can be made with stealth porting on LA heads.
Actual flow will vary with different casting numbers.