All the pans and interchangeable and the pickup tube on the oil pump goes to different lengths and angles to match. You can bolt any inline 103,104,603,606,613,648 oil pan to the engine. So you can do rear sump if you want. Engine mounts all bolt on in the same locations. So if one of these engines fits in the car. All of them do. Of course layout of other things may be different. ie intake, exhaust etc.
Also the 648 has a different bellhousing pattern so the bottom of the pan does not bolt to the transmission. You can just leave it or section it off and weld on from a compatible pan.