Thanks for your really constructive answer.I still believe that this frame is built for war, and I only go to the grocery store.

 

Steel doesn't care what you believe. People who aren't weldors have basis to form a "belief" so learn before daring to form an opinion! Make whatever you do strong and utterly reliable. If you aren't a metalworker consult those who are then learn to think like one, and not like a lesser creature. Everything you wish to do has been done countless times (in terms of weldments) so copy success and observe how aftermarket frames from proven makers like Paughco are designed.

You'll need a sound transition between square and round so study and post a build thread in an appropriate chopper venue to ask advice, and you can also ask the question in welding forums like Weldingweb or the Miller forums.