Jason,
I used Joel's approach a few years ago when I restored my heater box. Just used a loop of heater hose w/o the copper tube. While I was at it, I replaced the original transfer pipes behind the bulkhead with SS tubes. I was pleasantly surprised at the good condition of the old tubes.
Btw, I'd heard of the waterless coolant several years ago and decided against using it when others reminded me of galvanic corrosion issues with dissimilar metals and coolants. I basically decided that the original engineers had more experience in this arena than me, so I continue to change out the coolant every few years. Let me know if waterless coolants have improved in our application.