Thanks All;
Plus phone calls with Bruce F & Gary J.
I have a 3/16" split point drill that mic'd the same as my bolts. By carefully setting up my drill press and installing AN3 bolts as I drilled, I got a very snug fit on all and it turned out very well.
Maybe I got my self all worked up over a small issue, but the original H beam fit would be hard to duplicate to the center section clevis, Serious Pressure to get it right!
I then took the assembly to the airframe and installed it, the original bolts were a nice snug fit. I'm satisfied that I can continue with the clean-prime-rivet & bolt together part.
Then to drill/celco on the ribs and rear spar...
I'll be flying to Sedona in Brand X again this year, but I'll bring some progress pics to share around the wine table at the Sky Ranch.