What the heck!

at the risk of sounding stoopid......take the rail gaskets and switch them to opposite ends of the pan.....the end you are showing us in the pic goes to the front,the rubber part is designed to be crushed tight when installed but use a lil' dab of rtv where the rubber meet's the gasket in the corners.the 360 engine has a diffrent main cap than 273-340 but the timing cover end is the same as 273-340 and that is why the side pan gaskets don't go that way...hope this is helpful......I just reread.....fishy's right on the money