I have an early 01 HO, couple things to look for.
Find an 01.5 with the four wheel discs, it's worth it, I am not happy with the rear drums on mine.
You know about the Lift Pump, here is another option on fuel supply, get you two remaned Holley blues and put one in back by the fuel tank, that's what I have and I can't drop the FP gauge below 11 PSI pulling a grade with the house in tow. The other is for a spare.
Ware the 6th gear synchro, they are known for failing, if you come across one that has a bad synchro remember that it is a complete tranny tear down to replace it
OTOH, just float the gears, don't use that pedal to the left once you get moving and forget about it
On your power want's, a good free flowing air element, 4' or bigger exhaust, a set of 275's and a Comp box and there ya go. I have a set of DDIII's, BHAF, 5' pipe and a Raptor box (edge EZ clone) I have not been able to put it on the rollers but the consensus is right around 320-350. I can pull the house all day at 80mph running 20-22psi of boost and right around 1000 on egts with 3.54's. The HO's seem to really respond to a larger injector more than the SO's do so keep that in mind.
The 6spd is the way to go if you ask me, that extra gear in there just helps to get things moving faster.
The House=40ft Kountry Aire fiver, 16k empty, truck and camper went over the scales at 23k.
Just my .02 worth, hope it helps