M151-8 or Equivalent for Ampeg Cabinet

I have a 1998 Ampeg LGS-215 cabinet which has JBL speakers in it which sounds killer. From what I have learned about them, I beleive they are JBL M151-8 speakers. The last time I had them out of the cab to look at them, they looked like the pics I've seen of this model online (smooth cone, aluminum dust cap, vent on the back of the magnet, same sticker placement):

http://www.audioheritage.org/vbullet...1&d=1093438322
http://www.harmony-central.com/Event...nisher-Rig.jpg

My question for those in the know...

I also have a second regular Ampeg 215 cab that I would like to load with JBL speakers so I have a "matching pair" if you will - both sonicaly and cosmetically. The M151-8 is discontinued, so I am wondering what the closest equivalent is that I may be able to use - either vintage or modern. I've searched for a pair of M151-8's, but to no avail. I've seen E-140's come up on Ebay quite often but is there anything else I should consider even if I have to change out a paper dust cap for aluminum?

Any suggestions would be appreciated!

K or E 145 will extend lower than the 140, but I've always liked the sound of a bass guitar through the 140. Mind you, my bass is a 4 string. A 5 string, you may want to consider the 145 instead.

I'm currently using a Cabaret 4690 to play both my bass and guitar through using an early 60's Fender Bassman head (the 6G6 model). The original HF components were missing when I got the cabs and someone had replaced said units with an aftermarket horn loaded tweeter.

My next step is a pre-out jack from the Fender in order to connect to solid state power for when playing bass as these bassman units are beautiful sounding as a guitar amp, but lack the power supply stiffness or power output for a satisfactory bass amp.