Adaptors

Part of the problem will be that the adapters will push the wheels out another inch toward the outer body. The wheels and tires may not clear then.
A buddy has a 1970 Dart Swinger with a 340. I sold him a custom set of 15 X 6 rallye wheels with the small bolt pattern. The 235-60-15 tires are really close to the outer wheelhouse edge/lip. The front 215-65-15s are close to the top arch of the wheel opening when turning. Now imagine if those are now an inch further out.....Not good.
A billet adapter can be totally reliable and give zero trouble but you need the clearance to use them. CAST adapters are NOT a good option, the metal is nowhere near as strong as a billet piece.