Looks like I've found a good ratio for Unreal Engine. The grid x axis is reversed from H5 and Reach, so those values need to be positive instead of negative and vice versa. For example, a value of x: -264.2 in Halo Reach would be x: 2642 in Unreal Engine. No scaling is necessary: convert the file into FBX using 3DS Max and import it into Unreal. Note that you can use .obj files, but as SmokinBriz said above, they'll eat up your RAM and are much larger than FBX files. To more easily find coordinates, create a simple cube and scale it to 0.2 on all axis. This is the same size as the 2x2x2 cube in H5. The coordinates for its position are its center, so wherever the center of the cube is is where the coordinates will line up. Simply copy and paste!
I'd hate to bump an older topic, but this looks really cool. I never knew blender was actually free. Sound like something I might look into.
Yeah, and 3DS Max is also free for students. I've seen this start to catch in a few places and it's produced fantastic results which is really cool!
I think I finally got Midship from Halo 2 scaling correct. Still have a bit to finish it though. You guys should let me know about some feedback on it.