Bill, I apologize that your first post was overlooked; as you know, we have a bunch of knowledgeable people on this forum and sometimes that happens. What you did was bump it back to the top so people had another opportunity to see it. No worries!
You shouldn't have to beef anything up; many of these can bolt up in direct replacement for your standard pin box. I have heard rumors of folks complaining that EPB's can cause cracking and welds to break, but never experienced it or seen it myself and I know many folks who have them. BTW, here's a
LINK to a common replacement model. Once you get this mounted up, you'll likely need to re-adjust your fifth wheel hitch. Pics of your springs would be good, but from the sound of it, they need to be re-arched.
BTW, I'm sure you already know this, but it is better to tow with the rear-end slightly higher than the front than to tow with the rear lower than the front.