Seeing he wants what you have, I would make him drive to you, unless you're close. Make sure you have a good compression gauge handy. Try to get him to show you the old pistons, if they're pitted bad it means it was detonating bad. If it has a cool head you can always get bigger domes to get down to 93 octain.
I looked at both northern and central Mi CL and didn't see anything that matches your description, so I can't offer an opinion.
As to the Honda, I wonder if it was ever properly jetted for running in the summer?
JMHO, your results may, and will vary