What?! You seem to have a very own definition for EV -- or dynamic range, for that matter. Are you sure you are not speaking about Dmax, a totally different subject? Though, the Dmax is not 3.67, but nearer to 3.5, but I cannot figure out any other number that is even close to your 3.67. For log H, on the other hand, 3.67 is too much for any slide film for any purpose.
I think Stevie referred to 3.67 EV above middle gray before burning highlights, that is, you measure your highlights (the brightest part of the frame where you would consider a failure if you had no detail) and you open 3.6 stops at the very most. That's consistent with characteristic curves indicating a (total) dynamic between 6 and 7 stops.