I just fitted a .26 max to my revo a couple of weeks ago- it's possible that's not exactly the same mount as I have but it sure looks the same so I think it almost certainly is.
First thing- the hole is wide enough to provide some adjustment- it has WAY less than the stock mount, but there is enough there to get the engine in and get a decent mesh. Needed a tiny little shove to get the mesh, tendency to be tight as it's such a snug fit.
I mounted it with the 14 tooth clutch bell and then replaced with 17 tooth, worked fine (someone told me they have a 20T on theirs) which makes sense as the thing has ridiculous torque compared to the 3.3. Stock spur gear was fine.
Re the carb lever- it came out of the box pointing the wrong direction, just needed spinning round to fit before tightening it up. Does that help?
Apologies if that is not actually the same mount! I got mine off a guy on ebay, mount came with the engine, not labelled. As I say though, sure looks like that.
NOTES: I needs a 3 shoe clutch, it'll kill your stock clutch in no time.
Also, I ran it in then lasted 1 tank before I shredded my tranny.