Here's a couple of shots of my project to show the engine position. The sump is flush with the bottom of the chassis.
First is a close up of the nearside engine mount (early mock up). The second is a view down the chassis showing the gearbox mount. You can see that material was removed from the chassis, which was then re-enforced with a channel section welded to the outside.
View attachment 207574
View attachment 207575
That's my exhaust route but it's no use for the OP. My cross members are notched for the exhaust.