The length and width are fine. However, the height is a little high in my opinion, but may not affect a well acclimated adult.
Assuming your either going to get a well established adult, or a hatchling and raise it in something appropriately sized untill its big enough for that enclosure, i would suggest this...
since there has been a few sightings of "arborealness" in the curtus complex. Why not include a shelf about 4 x 2 feet on one end of the enclosure.
that way, your really only dealing with 1 1/2 feet of height (from your snakes perspective anyways), plus you have almost doubled the surface area for your large adult blood to roam.
Not only will this keep it busy, but will also take away from that stressful hieght in your enclosure.
Thats what i would do anyways....
Goodluck!!
Gvg