Ekco EV55 using 6550's in place of KT88


I purchased an EKCO EV55SE from a fellow Audiogon member and since then I've been trying to find out if I can substitute NOS GE 6550's for the KT88's ? I swapped the EKCO labeled KT88's for a quad of Gold Lions but really want to try the GE's also. The previous owner has been a tremendous help going way beyond anything I could ask for. I've contacted IAG via email on a couple of occasions and even called a dealer in the UK but can't seem to get an answer. The previous owner suggested contacting  USA Tube audio as they are a supposed dealer. Well, that was a lesson in futility. No help they just trashed the amp and tried to steer me to another product line they carry. I believe the swap would not be an issue but would like to get some verification before I swap. Don't want to hurt the amp nor lose a tube or two as a result. Thanks.
mets1p
I finally swapped in the GE 6550's. Only had a chance to listen for about an hour last night but so far so good. Thanks for the feedback to all who replied !!
When I had Dyn C1's my favorite was the TS 6550 solid black and grey plates. Mids that remind me of EL34's but with much better lows and more power.
No worries!

The difference is that the KT88 is supposed to be more linear. But if you have real GE 6550s, they may work better simply because they are a better tube. Have fun!
If I remember correctly the KT88 was made as a replacement/substitute for the 6550. Should be fine
Thanks for looking I know this is a tough one if only because the amp is not well known. I'll eventually just replace the tubes and hope nothing goes nuclear on me !!