I just want to make sure I understand this right, so I made a quick drawing. Does this jive with what everyone else is talking about?

 

No need to make your own... there are a bunch of them out there already but it looks like you've got it.

https://www.rsracing.com/tech-wheel.html

 

Yep, thanks. I've looked at a couple posted here, but I have been having a hard time finding a difinitive answer to the distance from the inboard bead seat to the inside edge

 

 

I have a model of a 18x7.5 rim that shows 6" BS/+44mm Offset. This seems like it's different from what most here post. The wheel has 3 part numbers cast into it:
9L34-1007-HB
9L34-1007-NB
AL34-1007-HA

I'm not sure which models these go on, however.