I have a 4R70W installed with a manual valve body, trans brake, overdrive, and lock up converter.
The lock up and overdrive are on a switch.

Is it a bad idea to have both on one switch?
I have a single disc converter, so it can't handle full throttle runs locked up.
Overdrive would probably explode under full throttle.

I couldn't think of a reason not to put them on the same switch, seeing as I wouldn't use either unless cruising on the highway.
Unless overdrive needs to be engaged before locking the converter.... but I know you can shift with the converter locked, so that doesn't even seem to be an issue.

Thoughts?