Wait a minute, rear sump would clear the k frame but the center link of the steering would be an issue. Either way you have to stick with a center sump.
I know that a 6 qt '70 or '71 hemi pan will fit. For some reason my original '71 383 Challenger came from the factory with a 6 qt hemi pan on it and it has no clearance issues. 7 qts with the filter which is 2 qts more than the stock pan, I like it.
You may want to consider a low profile pan, like a Milodon, which has side kick outs for increased capacity (7 qt) while still having decent ground clearance.