Interesting idea with the 0w40 / 5w40. Is this to avoid burning oil at higher temps but still having good freezing weather starts?Not all 0W-20 oils are created equal. Mobil 1 EP 0W-20 and Castrol EP 0W-20 are some of the best. Some of them aren't that great though. Not bashing any particular brand, it's just that products have to meet price points. Disclaimer: even the cheapest 0W-20 might be great for a new engine, but with your high mileage, I doubt it.
If anything, go the other way. I would consider Mobil 1 FS 0W-40 or 5W-40 depending on your climate to make up for some of the engine wear. Sell 0W-20, or better, donate it and use it as a tax write-off.