Americans Vance Breeze and Michael Ross rode a pair of Heavy harley's in the 1982 Classic, Breeze finishing 38th with an average of 83 mph, Ross retired. David Hughes rode one in the 1975 Classic, also retiring. I have a shot of Hughes well airborne at Ballaugh, bet that made the ground shake when gravity took over again!
Breeze fastest lap 26.11.4, Ross did not complete a lap. David Hughes 23.14.8.
I'm sure anyone who rode the '82 Classic would class it a proper race!
A fully searchable TT database can be found at:
http://www.gov.im/mnh/collections/tt/search.xml
Let me know of mistakes so we can put them right!