Here is the email i received from him on the specs.
James - here's the spec info on the Magnum heads. The casting numbers are 671 and 466.
Valves Intake Exhaust
Installed stem height 1.783-1.880" 1.783-1.880"
Stem Diameter .372-.373" 372-.373"
Total Lenght 4.969-4.994" 4.978-5.012
Head diameter 1.88" 1.617"
Springs
Installed height 1.640" 1.640"
Open Test Pressure 200 lbs. @ 1.212"
Closed Test Pressur 85 lbs. @ 1.640"
The following flow information I found on the internet.
INTAKE PORT
LIFT CFM
0.100 60
0.200 120
0.300 168
0.400 195
0.500 202
0.600 194
EXHAUST PORT
LIFT CFM
0.100 59
0.200 113
0.300 142
0.400 148
0.500 150
0.600 151
Hope this helps!
Mike
Ideal Cylinder Head