Congrats on your purchase, and welcome to the family.
A few things you should know if you didn't already...
First, if the bus is from the northern part of the country (sounds like it, since you are in CT), be on the lookout for rust, it is likely to have some, and it is better to deal with it prior to conversion than to have to pull things apart to fix it later.
'02+ diesels had emissions controls that can be costly to fix. The T444E may or may not have had any of this, as I understand it was phased out for the 6.0L VT345, and quite frankly, I'm surprised an '03 would have had a T444E, Ford started using the newer engine that year.
You should also know that not all Allison transmissions are created equal. The AT545 is very basic, somewhat weak, and very common. The MT643 / 2000 / MD6030 are much better. AT545 is fine if you're not doing a lot of driving, but the MT643 by comparison has a lockup torque convertor and if memory serves, is a 5-speed versus the AT545's 4.
Tell us more about your bus! Pics or it didn't happen!