Change from 23 to 18 spline clutch disk

I'm lining up parts I need to swap my 833 for an PP 855. I remembered reading (I thought) that Passon would supply a 23 spline model but, they don't.

What do I need to know to get an 18 spline disk that will replace my A-body 23-spline setup? Any BB 18 spline will do? Any particular disk that's loved the BB world around?

It's been some years since I was last into my clutch. I recall something about having a 11" pressure plate and a 10.5" disk? That may have nothing to do with an 18-spline choice.

I should know this stuff. I've built a couple of motors and swapped a few 833's..but the last of that was a long time ago. I doubt my Duster has 1000 miles on it in the last 10-15 years. I'm looking to change that..but I want to keep my 4.56 gearset, too.

**Edit**
This just occurred to me: The 23 spline being a 1" shaft and the 18 spline being 1-3/16"...my TO bearing can't work, can it? Passon didn't mention that needing to change.

Thanks.