the rear "half moon" on the 360 pan is different, (to match the curve on the #5 main cap), smaller iirc. & on the front seal mockup the seal into the pan half moon cutout & you dont want the seal ends way up higher than flush with the oil pan rail & some seals vary alot, some need the end flats trimmed a bit, though you do need some "crush" & some aftermarket pans need the 2 mini holes for the seal nubs to be enlarged or elongated for the seal to have a dead on fit, leaks are a pain but disregard if you have the stock pan but I just run into this with an aftermarket pan. sometimes the pan side gaskets need trimmed where they meet the rear main seal ends, Mockup & see what you see. On a SB, dry mockup/fitment is your friend. EDIT I missed that you ain't changing the pan