Which VHO ballast?? Help

[smokinreefer]

is there a workhorse that will run 6' bulbs?

i already have 2 40W NO actinics running on my tank now, can i just swap out the NO ballast for a WH7 and use the existing wiring and endcaps to overrun the bulbs that i am currently using?

adding stronger actinics was last on my list of things to do, but if i can just swap out a $55 ballast and get near VHO output from cheap actinics, then that would be cool.

thanks for the input, much appreciated.