Dog,
May I recommend a call to Jason Hawk at Hawk Engineering in Jackson MO?
http://www.hawkengineering.com/
He has a good 7 years experience at building this type of HDT conversion and he may be able to help you out with the conundrum.
I just finished my conversion with him and was a great experience. Not to mention I have exactly the truck we wanted. He has a 2003-5 vintage T2000 conversion underway in his shop that is for sale. It is probably about 70% complete; this is great if you like the basic direction he is going. You end up with a shorter lead-time and you still have the ability to have it your way. The value of ability to complete the coach with a fare amount of personalization is high.
The prices that are discussed by GEO are in-line with our experience or maybe a bit high for where we ended up.
Feel free to contact me if you want specifics of our project…
Jim