Changing the shift lever is by far the better choice. But you really should hang onto the 65 C4. They were unique, even the 66 was different. Then of course there's the shift pattern, which is different in the 77.
The 65 is
And the 77 is
In the 65-66, the O is normal drive.
Amateur restorer. Well, sometimes I have been paid for it. But not right now.