For mating, I have some high temp thermally conductive epoxy coming in. Will use it to contour the top of the heat sink to match perfectly to the oil pan.
Duralco 132-1 (due 5/1)
High Temperature Adhesives and Epoxies, Ceramics, Insulation, Epoxies and Epoxy
Then, yes, a little thermal conductive grease to go between the two. I think I have some in my desk somewhere so I haven't bought any yet.
Attachment will be by springs. There's 2 holes in front of the pan and 2 threaded holes behind. I'll use a stud with a hole in it in the threaded holes. Loktite-ed in. Shooting for about 30# of pressure (4-5 gs) against the pan.
It may fit under the cover without mod. It's going to be close. I'll try it with the cover first. It looks like there should be some forced air flow through that area without mods. If it's not enough I'll be making a custom cover. Saw in another thread the dealer wants $950 for one. Another rip-off.