That is true any 650 unit engine from 63 on will go in there. It is best to go with a later 60s motor. They are much easier to time. Earlier 60s need a degree disc to time later they had a fireing position lock to time. Also before 72 since in 72 they went to push in exhaust and that tended to wear the ports in the head. Earlier heads will fit later motors so if you want a later 5 spd engine you should find an earlier head or have spigot welded on. They are available.

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