Ray, you are not in the woods by yourself, we might lurk and read, but if ya need something that I can help with just post, I get by here 'bout once a day. I cut my frame rails with a Dewalt saw-zall and 3 $2.00 each metal blades, it took around one song on the radio per cut, but 3 beers to gather the courage, and 1 afterwards to look at what I did and comment "what did you just do?"
I'm going out on a limb but looking at your weight numbers, I may get time to play with them soon, but you should be all right as long as you keep those water tanks full. You might think about relocating your fuel tanks further back, perhaps right in front of the drivers. The bus was designed to haul a load of people, and the over hang was to offset the steering axle. If you look at some of the truck conversions, they have very little overhang. this makes them ft axle heavy UNLESS they are pulling the nose heavy stacker trailer that most were designed to pull. You might be close with that big block diesel. But if you make sure the water is full to teeter totter the weight back (if you ever have to scale it)
Personally, I'd run her nearly out of fuel, fill the water, have the wife and kids to the back and get a certified scale ticket. Keep it with you if anyone ever asks you about the ft axle weight.
blizz