[Amps] 3-500Z to 3CX1200D7

[PlanerGuy at aol.com]

What is generally involved with changing from a pair of 3-500Z tubes to a  
pair 
of 3CX1200D7's, not including HV power supply concerns?
 
Reason I ask is that I was offered a set of 100% 3CX1200D7 pulls, and  
thought 
they'd might work out pretty well in a Henry 2K ClassicX.
 
Thanks for the space here.
 
KC8GIA