Question about tire size on 74 Dart

I have done the following on my Dart
New front end rebuild, new sway bars front and rear, New Hotchkis rear correcting and lowering leaf srings, Bilstein shocks.

I want this car to ride quiet and smooth. I have stock 14's now and going to 15 Rallyes but stuck on width size.

I've asked this before but want to make sure and was hoping someone has done this. It's for long freeway drives so I want it to drive right. Will most likely go with Michelins.