If you're going Heidts make sure you ask them which pans fit with their kit. Rod & Custom has a list that fits with their suspension. "rear sump" alone may not be enough.Uhhhh....one more small issue too. What about the front mounted dip stick tube and dipstick? With the front sump gone, the stick won't go in all the way will it? And even if it did, the front sump on a rear sump pan is just big enough to cover the oil pump. Considering I'm running a late model block I have the option of using the stock post '86 dip stick location, but what about those with pre '86 blocks?
I think you have to run a special pan with custom dipstick location built into the side of the pan?
FWIW, Summit Racing carries a new Ford pan, pick up and side of engine block dipstick assy for $100. I'm about to go that route unless I can find a good used one.
EDIT: Did a little Googling and found out that a Canton aftermarket pan for a Fox Mustang comes with a bung to mount a dipstick into. But you have to run the Canton Dip stick assy.