Since I am a diligent research monkey I kept digging and finally found a document with a definite radius call on the south right of way. Yes there are spirals but one course goes through my entire project area.
I jumped all over it, added 33 feet to it for center, drew it in on my points and that thing fit amazingly well.
The client loses another tenth or so to the RR, but I felt all warm and fuzzy knowing that I had something definite to work with.
I would have stood by my first method had this document not been recovered, however it is nice when something pops up that truly brings it all together.