6SN7 equivalent's, help need it

I am not going to put them in my amp before I am 100% sure of it. These tubes are the rarest I came across, same as Telefunkens 6SN7 for example.
So far, got the info from 2 places where folks are think/tell it can be used, but to me, only data sheet can tell.

Another interesting note. Spoke to some pro and he think he owns a pair of the same kind, but only RFT branded, but he is not sure yet, will keep in touch with him to see if anything comes up.

What do you think guys, if I am going to test them like 6SN7 type, can this cause the problems, for tube or for an tester?

THX

@Jaiello

Thanks, indeed, very helpful. Unfortunately, they do not have anything about this kind, at least when I use their tube data.

THX

@Mechans

Thanks for update, all these are known by me and I am aware of the differences, but again, thanks!

I was talking to some guy from Czech Rep and he told me that 6CC10 probably 6CC1, but Czech's didnt use the same full code. On the other hand, still didnt found anyone who owns an data sheet, but the pin connections are the same as 6SN7 type.

THX