4R pan or aftermarket? If the former, you know the answer.
If the latter:
I would contact the pan manufacturer and see what they recommend. A filter for a 4R70 (with their inhernantly deeper sump) might get you closer to the bottom, but we hate 'guessing' on that kind of stuff (hence my thinking that the pan manufacturer should know straight-up what's best).
Its the B&M pan. I have the 4R70W filter in there that gets in deeper than the aode ones, but i was wondering if there was anything better. B&M makes some extension for the scavenging tube on the filter (i just made that up, dont really know what its called), but I dont really like the idea of just an extension...