Finally got all the holes drilled. Boogered up the first 1 3/8" hole I tried on a 2.5" x 2.5" (5/8" thick) piece. The hole saw tore up the arbor. Spent half a day trying to find more 5/8, but got a foot long piece this time. The extra was cheaper than the cut. The step drill worked fine. Took almost a full day to measure and drill all the holes...
A buddy in the club is a certified welder, so he's got the pieces now, then it should come home for paint.
The guy at Fastenal is a club member also. He just wasn't working the day I bought the hardware, so now I get the club discount. Some of the extra bolts will be passed on to club members, as there are at least three guys that want to build one also, once they see how this turns out.
My saving grace on this project is my neighbor. He's a retired engineer, and I wouldn't have been able to do this as easily w/o the use of his horizontal bandsaw, drilling/milling machine, and the large size drill bits. Thx Al!