Yes, I did NOT remove the oil drain plug, and YES, since I didn't remove the drain plug and was going to have a half of a Qt of oil leftover I decided it was prudent to use it as a rinse . (The half of a quart only cost $2.35 )
Well today I buttoned up the Buck 400 after the oil change, The old oil was really black and and a little over a quart was sucked out at about 150 degrees F after warming the engine up for 10 minutes. Then I added the 1/2 Qt of oil for the rinse. the engine was still warm and the pump pumped almost all of the 1/2 rinse Quart out.
I did have time for a test ride. I warmed the engine up at an idle for a couple minutes while checking for anything falling off or any leaks, everything is okay, I had a bit of jerking backing out of the shop and then in high gear for a couple of starts and stops then it started smoothing out, well as smooth as can can be expected, as the clutch has to have enough RPMs to spin up and engage the drive. after a half mile ride and a complete stop and start it is doing okay. the odometer showed 207 and I reckon in the area of 20 to 30 hours before this it's first oil change.