So, I tow a lot of different things with the 38A, which has the 340 Cummins and Allison 2500. So, we have even more bus weight than you do to begin with.....
Most things we tow are well under 5K but there is a large trailer with may be a few ounces over 5000 at times....
All of it tows well.
Handling wise you're not going to notice the difference. performance wise I don't think you will either. It may be a hair slower but you won't be causing a backup on the interstate.
Allegedly the weak link in the chain is the Allison. I have my transmission temp up on one of the 3 bars in view of my LBCU at all times and I have never seen anything in excess of 195º which is well within spec.
I'd say go for it, don't think you'll be disappointed.