[Amps] Modifying Acom 1000 for a different tube

[krishna kanakasapapathi]

With the price of the GU-74b's going up and the supply shrinking and is 
almost turning out to become
yet another 3cx800, i have the following questions

a) What would be a good tube to replace the 4cx800/GU-74b in an Acom 1000?
b) Minimal retrofit/gut down work
c) Assuming the retrofit would be compatible to let Acom put out a new 
firmware

I guess selling retrofit kits would ensure
a) Acom generates some revenue or is a parallel value chain
b)Builds confidence among its customers
c)Keeps the resale price of the Acom's stable over time.

Any thoughts?
73s
krish
w4vku