Have a local lead on a K-151 18" driver that I’m considering for a bass/organ rig. How do these compare with the E-155? Would I expect to hear a much lower and dynamic bass response from the 18” vs. the 15" E145?

For my project at this point I'm leaning towards. one cabinet housing an 18" and the other with a E145/E140, 2118h, and a 2404 horn with a crossover that will allow turning off the 2404 for bass guitar use.
Are there any other 18/15" drivers that could be good for the ultra lows in a small box?
Any opinions and suggestions are greatly appreciated!