Hi M,
the EF86 can be a very useful tube.
When I converted my JE labs 300b to a WE 91 type I had to decide between the ef and the 6js7.
Good ef86’s were not cheep,
In the end the 6js7 would fill the empty octal hole with no fuss and I did score some very nice old, old ,stock glass 6js7. So there I went.Get them if you can, contrary to popular opinion, pentodes are not evil.
If you are not inclined to use them as an input stage. Should you ever be inclined to use a Gary Pimm pentode CCS, your good to go…John