Need speaker help (amp forum)

I have an older ampeg 1510e, 8ohm cab with a 15 and a 10, no tweeter (not the 1510he). I can't find squat on it online or on this website. The 10" speaker is dead, and for all I know, has been for some time.

The 15 is a 16ohm and the 10 is an 8ohm, wired in parallel which just surprised me.

I want to replace the 10 and the obvious would be a 16ohm, run parallel making a 8ohm cab, but I'm thinking of replacing the 15 as well for 2 x 8ohm making a 4ohm cab. I like warm sounding, punchy, not brittle and was thinking of the eminence delta 15LFA and Legend BP102.

Juice is not an issue with a demeter tube pre running into a Crest CA-9. SUGGESTIONS?