Do you want manual only or do you want auto shifts? Either way can be done, but as suggested above, you do need to change the way you have the throttle lever set up now.

On my last blower car which was primarily a street car, I started with a cable kick down which worked okay. But changed to a forward manual valve body. I usually like to shift the car manually anyway and the tranny just reacts quicker and more consistently with the manual valve body.

I even had A&A build a manual valve body for the 518 in my current Cuda street car. They softened the 1-2 shift and the reverse engagement so that they weren't banging all the time. It makes for a good combination on a street car.

Plenty of choices for you once you make the decision on which way you want to go.