Thanks to all. BillR, Gary, Dave, BobT, rzbill, and Steve. Great to have experience, analysis and
data (Andy). Lower DA the better, apparently. I had thought that the Vans top speed numbers were at SL, standard day, but could not find any documentation. Steve, thanks for the analysis, and Andy for corroborating data.
BillR, according to the SL gain over max cruise, I think Vne (200KTAS) won't be passed, but closer than I thought. Pretty happy for a 180 hp engine.
Winter weather should bring some test opportunities, but maybe I should go find a beach