Power tailgate window regulator
 

Probably not the right area to post this question, so, sorry in advance! Question is; Can the 'power' tailgate window regulator for the 64-65 Chevelle wagon be converted to accept the non power crank handle?

I'm pretty sure '64-67 are the same.
And the answer to your question is NO.
I converted the power tailgate window in my '66 wagon to a manual. Totally different regulator. Bought a complete tailgate to use as a donor.
In fact, I still have the power regulator...minus the motor. Which BTW a working replacement is impossible to find. :( And the sole reason for me to convert to manual.

That's exactly why I'm thinking manual!!