They look good except for the body riding high. Thats the problem with most all slot car bodies I've tried using. They just don't have much room in the upper body or canopy. And with an SE chassis, the problem is worse. I'd suggest putting those types of bodies on the new Pixar Zips. They have the old style chassis and with the PCB cover removed, you can get the body very low.
Or, you can just call them your version of off road NASCAR.
As to mounting. You have to either cut, or build your own slots into the front and rear of the body so that they align with the tabs on the chassis. You can do this right in the front and rear of the body if the chassis fits perfect lengthwize. But, if it doesn't and is to short, you have to build up one of the slots with styrene or cut one out of an old body and glue it in there. I do this with the rear tab if the body is to long. If it is to short, you cut the slots in the body front and back and trim the tabs until it will slip into the slots tightly. That's about it outside of using a little imagination.