Will GM 200r4 work with factory floor shift location?

All your measurements are pretty close to what I got. Drilling the GM tranny fitting (large fitting) shouldn't be an issue as there seems to be plenty of material to go out to .250". It's the 1/8" pipe that I worry about. But you can experiment and the worse that can happen is that the 1/8" pipe will snap when you try and torque into the radiator. If you use liquid Teflon on the threads you won't have to torque it as tight. You do know that the GM tranny lines are nothing more than brake lines from Orielly's, pretty common (another reason I switched).
In reality, to be precise, the Mopar fitting is too small (ID) on the inverted flare end. the 1/8" pipe end is much larger than the inverted flare end. But it makes no difference where the restriction is because you can't use the Mopar fitting with GM lines anyway. There's a formula out there some where that can tell you how much extra flow/volume you get when you increase the pipe diameter by X. I can't remember the formula but if memory serves me, keeping the pressure the same in both cases - -- if you increase the pipe diameter by 2 times your flow/volume increases 16 times!!!. I know that if you increase the diameter on from .220 to .250 it should increase flow/volume by at least 12-15 percent, which is a lot in a transmission cooling system.

treblig