I am running a 5.0L engine with a deep rear sump oil pan from Canton (I am also running a Heidt's Hot Rod Front End).
However, my question is we ran the stock 5.0L oil pump pick up, would this be a problem?
If the Canton sump is lower than the stock oil pan then you'll need a pickup that's lower also. If too much space is between the bottom of the pan and the pickup screen you risk sucking air into the pump from the oil moving around in the pan, but you don't want it touching the pan either. Ideally there should be minimum 1/8" between the pan and screen, but a good rule of thumb is to install the pan with no gasket and adjust the screen so it is close but not hitting the pan, that way when the gasket is in place you have the thickness of the gasket as clearence.