Need more info. What are they being useed for i.e listening, stuydio recording/playbvack, do they need to be portable, dsize of room balance of speaker set.

Hence replacing something changes ambiance straighyt away. you want to try an marry the replacement with what your ear wants to hear even if it requires to buy vintage restored. Its simply a mater of what you expect from this oucome of change.

The other thing is value for what you get from this change. If your current woofers are not meeting benchmark you need to nut out why this is the case and narrow your search of replacement to find the right result. I know that IIIB's are known to be too bright so that isn't useful but ther are solutions in buying a more bass response speaker set where the curve is susatained of the values you seek. All high quality speakers have several respoinbse curve tests you can measure against what is missing. That helps you to eliminate what doesnt meet your requirement.

If I spout off Speakers for you to look at it quite ignorant because I dont use your space and you hear differently to me in that space. But there are very good reputable nobody maker who may serve well to invest time to look at their builds because buyting stuff for audio quality is very focused for individuals. You must do your homework and dont buy anything unless you can actually test it and hear the solution for yourself. Any audiophile can sweetlip you a solution but i'm an audio engineer and I build studios. Is a minefield if ears which argue their own balance. The sensible solution is to hire, test, evaluate and repeat till it solved. I dont talk cost when most auduio system are generally a serios build but are almost a oneoff process, in context you may spend a lot but what do you want to hear from your system?