That's the way I read it too, Rusty.
I just wonder why its OK to fit a later engine, but not to convert a linkage bike or a disc-braked bike?
At the end of the day, you'll still be able to say "Yep, she's got air cooling, no linkage and drum brakes, so she's an Evo bike alright!".
I agree totally with Evo550's most recent post, FWIW.
If the argument is "We're not in it for trophies, we just want to go for a ride on a cool bike", then you've got no reason to want to ride the bike in pre-85 where it is clearly eligible and doesn't upset anyone.