There are any number of good designs you could use for a 115 or 112 stand alone cab. The trouble is you won't have any way of knowing how it will interact with your existing cab. This is why it's being suggested to simply get another identical cab-it's guaranteed to work and sound just like a bigger version of what you've got now. Anything else is a crapshoot. Might be great, might suck.
Originally Posted by Bassist4Eris
My reggae skills are rudimentary enough that I just play whatever the original guy played. :)