My unit is an original HA 2500 (push pull, four nuvistors) that was upgraded to 3000 status by KS Park, but uses just two 6cw4 now in single ended. I think the 7895 may be electrically similar, but I haven't tried one.
The standard mass production green label military nuvistors sound great, but have an upper midrange emphasis. I believe the ones in my unit are originally Sylvania green label of USA military boxed origin. I think the yellow labels may be Sylvanias of Dutch Philips origin. The nuvistors seem to have the same variations of mixing of manufacturers and mixed up labels as other tubes, very confusing. Also, nuvistors don't have a lot of information about them. I was just surprised that they do sound different, maybe like the variations between Western Electric 417a and5842 small tube types.
Unfortunately, it is going to be a shot in the dark due to lack of info and general feedback from the audio internet community. The good news, nuvistors are relatively inexpensive and you can buy a bunch and experiment.
One of the problems with nuvistors is they have those tiny brass pins that corrode easily and make them noisy. I use a fine grit diamond metal nail file to gently brush the pins, coat them lightly with contact enhancer, and it tends to keep their inherent noise level down. This should probably be done every few months to year depending on how the noise level increases.