Here ya go, they should be #706

Stock 5.3 Heads
Chamber 61.15 cc 0.100 0.200 0.300 0.400 0.500 0.550 0.600
Intake 200 cc 63 128 179 210 218 221 226
Exhaust 70 cc 54 93 121 145 163 168 174
Valve Diameter Intake 1.89"
Valve Diameter Exhaust 1.55"
Part Number 12559852, 12561706