I have 1.5 inch polyiso on the outside of my sheathing that comes all the way down to 3" xps foam on my poured walls.  Since the Polyiso is a vabor barrier I understand that clsoed cell would create a sandwich of two vapor barriers on my sheathing and that would not be good.  So, can I use open cell in this area?  If so do I need to be careful of how thick it is?  I ask about the thickness because I have 10" poured walls and if there is an issue with a full cavity fill in the rim board voids between 14" tall TGI floor joists then I would like to know ahead of time.  Is there a better way to insulate here that doesn't involve cut and cobble method?

Closed cell foam won't create a vapor barrier- it's semi-permeable at 1" and would be fine even at 2", fattening out the R to the interior side with damp sprayed cellulose or carefully trimmed rock wool batt.

At 1" closed cell foam will run between 0.8-1.2 perms. This is 2-3x more vapor permeable than asphalted kraft facers on batts- it won't be trapping moisture in the rim joist.

With 1.5" (R10) of iso on the exterior, 1.5" of band joist (R2) and 1" (R6) of closed cell on the interior side, you can safely put ~R25 of fiber insulation in the remaining 7.5" of foundation thickness even without interior side air-barriers (but interior air-barriers are still worthwhile.)

@Dana
Thanks. I needed a straight answer and you provided it.
2 inches of closed cell is fine.

Now, dare I ask if I could finish that spot with an additional 7.5 inches of open cell? Or could I even use the open cell for the entire void directly up against the rim board?
Also not sure how a guy would use and interior air barrier in this area because the this would make it difficult to fasten anything because of their shape

If you go with open cell foam use 0.7lb density or higher foam, and NOT half-pound goods. Give it a few weeks or even month to cure/dry then spray it with a "vapor barrier latex" paint.

The v.b. latex does not perform to spec when sprayed on foam (it runs about 0.5 perms when applied to paper-faced wallboard), but it will lowerthe permeance. At 0.7lbs density the foam itself is about 2.8-3 perms @ 7.5-9", and the v.b. latex would cut that to under 2, which is sufficiently low vapor permeance to be protective in your stackup & climate.

I see, sounds to me like the closed cell at 2" thick is the answer, then wet sprayed cellulose to fill the whole void. I like it. Thanks Dana