Cobraman,
I have a 390fe with the Canton T-Pan. It is the same depth as a stock
oil pan but has the wings that hold the extra capacity. I also have a 28" tall tire. My bell housing has been trimmed flat on the bottom where the flange use to hang down. I measure close to 27" from the ground up to the top of the inside of my wheel wells. I probably have 4 1/2"-5" of ground clearance. I have rubbed on occasion but go slow over the bumps and try and go at a diagonal to them. Or you could get a Hummer. Just kidding.
John