I am planning on building a new house in Indianapolis, IN (southern part of climate zone 5) and want to make it very green but also want to keep it on a relatively low budget. I am considering a double stud wall assembly listed from exterior to interior below:

Gapped Rain Screen Cladding (0.34)
1x Furring and Air Space (1.00)
1/2″ Huberwood Zip System Sheathing with Taped Joints (0.62)
2×3 Advanced Framed Wall @ 24″ OC Dense Packed with Cellulose (9.25)
2.5″ Cavity with Dense Packed Cellulose (9.25)
1/2″ OSB (or plywood) with Taped Joints (0.62)
2×6 Advanced Framed Wall @ 24″ OC Dense Packed with Cellulose (20.35)
1/2″ Drywall (0.45)

Based on my research this wall should achieve an R-Value of 42.73 including air films. Is this wall assembly a good choice or is it over kill for my climate zone? Is there a certain R-Value at which point there is more insulation than needed?