My best advice is do not cut the firewall. It can turn into a nightmare. Tweak the other stuff like HOSS said. Re-configure the oil pan or find another one from another application and use the pick-up tube that came with it. Be sure to leave 1/4" to 3/8" between the bottom of the pickup screen and the floor of the oil pan. Use a little pyramid of modeling clay stuck to the screen and gently put the pan in place, then remove to check clearance.