ID these heads?
All production 340-6 heads were 915 and had "360" cast into them but machined for the rockers and 2.02 valves. I never knew of any differences between J, Z, O, etc. However, there were a few VERY early T/A style heads that were 894 castings machined to accept offset rockers. They may have been over-(or under:rolleyes:)-the-counter, not OEM.
All production 340-6 heads were 915 and had "360" cast into them but machined for the rockers and 2.02 valves. I never knew of any differences between J, Z, O, etc. However, there were a few VERY early T/A style heads that were 894 castings machined to accept offset rockers. They may have been over-(or under:rolleyes:)-the-counter, not OEM.