power tubes for ARC VT130?

i've retubed my LS 5 w/ 7308s & was stunned by the improvement. i then changed out the 6922's in the input stage of my VT 130 & obtained a similarly huge improvement. it may be my imagination but i'm convinced & hooked. now i'd like to change out my 6550s. what brand or types should i look for? also, any ideas on how to get explicit info on how a newby could rebias this amp?
I just sold a VT130 and that amp must be rebiased even when replacing the 6922 (6DJ8) tubes as well as the 12BH7's. As far as changing from a 6550c to KT88's or KT90's you should probably check with Audio Research first. The owners manual, if my mind serves me, correctly says you can, BUT a friend of mine did it to his and it did not like them at all and the result was they took out a couple of resistor's and one of the fets. Biasing that amp is pretty easy, but you do have to know where the pick up points are for the meter probes and which two of the four pots to adjust, adjusting the wrong ones can create a whole new set of problems. When you contact Audio Research for tubes alternatives buy one of the service manuals, I think it was only like $12.00, there is a diagram in the manual for biasing and also telling you which bias pots to adjust...Good luck
I don't know how they'd be in your VT-130, but in my VT-100, I love the ElectroHarmonix 6550s. Depending on your taste, if you like a real laid back sound, they might not be to your liking. I tried Svetlana KT88s in the VT-100, and I was not impressed. They were too distant and rolled off and the bass was not nearly as strong. I have a source to get the EH 6550s from, so email me if you decide to go that route. I, too, would be careful with using KT88 or KT90 in AR amps. Too many people have had resistors blow out with them.