I concur but, and maybe I'm mistaken so correct me if so, but I thought the Point Beach was an aluminum bike. I know many have been built but I tend to shy away from them because I like to weld engine mounts, tensioner brackets, etc. and I've never master the art of welding aluminum even though I have the equipment to do it.
There used to be a Schwinn called the Jaguar but it is no longer in production but it was replaced by the South Port. Same bike, different color scheme. They were good platforms for motorizing. The Cranbrook has been used many times and mostly successfully. I was just never impressed with some of the factory welds on the 'Cranny' but I've never heard of a frame failure on one.
Asking for opinions on bikes is going to get you numerous suggestions and comments. There are so many good candidates out there and so many have been used by our members that everyone will suggest their favorites.
Good luck and keep us informed on the progress of your build.
I'll also welcome you to the forum. We're glad you've joined us.
Tom