what kind of Guarentee are you looking for?
New sensor has stockpiles of old oddball tubes. if you go to an Electro harmonix dealer, they should be able to show you what kind of are available and what price.
I could tell you if they stock the ones you need if you have the numbers.
you could also try Doug's Tubes (
www.dougstubes.com)
he tests all his stuff. he was recommended to me by the guys at Groovetubes.
also Vacuum tube valley (
www.vacuumtube.com) has lots of old tubes
as well as Angela Audio (
www.angela.com)
I've ordered from all of them and had good experiences.