#15 heads were produced two years only and produced in the small valve 1.96/1.66 press in stud.
The date codes you provided are consistent with a #16 head for 1968. Your block date is L207 is December 20 1967 (for 68 model year) Your intake is dated 7 days prior to block (common date spread) and your heads are L067 and L197 which again, is consistant with your block and intake dates.
The number on the center ports...Sometimes the 6 look like a 5 and vice versa and can appear that way possibly due to rust, scale or weathering.
Is it possible those are 1968 #15 heads instead of the correct #16 head? sure. Would that engine have come that way from the factory, a resounding and firm NO...and that includes the exhaust manifolds.
One of two things. Someone along the way lost the correct #16 heads and found a set of closely dated #15 heads OR the 5 is actually a 6.
A very simple and very quick answer can be had in under 5 minutes. Take the valve cover off and look at the studs and guide plates. press in studs have their guide plates secured to head by 7/16" bolts. Large valve #16 heads, the screw in studs hold the pushrod guide plate to head.
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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.
