Well, late this afternoon I dove into these heavy limbs just to see how much weight I could take off of them. Ended up dropping 13# off of them and I don't feel safe going any further than that.
For reference.
1- I narrowed them up, A LOT, down to 5/8" at the base of string grooves and roughly 1.125 at the end of the butt wedge. Still fairly stable and tracking good. That netted me 4#
2- I sanded about .008 off both the belly and the back for a total of .016 off the working section of the limbs. That netted another 9#
Any further than that and I'm afraid I'm gonna get too thin on the glass without knowing it.
Off to start another set of limbs or I've got another bow that is about half done that I know would hit weight. It's a looker too. I might be able to flush limbs with that one. I've never tried that before.