I don't think any heads had threaded bolt holes. On some, the center exhaust bolt has a threaded top for securing the heat shroud....think that's what that was for.
For proper lengths, place all the bolts in heads where each has the same length on the mating surface side. All will have same length threading into block.
Si Vis Pacem Parabellum
1967 Starlight black PMD Engineering 400 Auto 1968 Alpine Blue 400 4 speed 1968 Verdoro Green 400 HO 4 speed 2013 1LE 2SS/RS Inferno Orange Camaro.
