I thought I would bring this thread up to speed now that I have tried a couple of suggestions. First, I couldn't find the actual Castrol product except on eBay and no one would ship it to the USA. Someone finally suggested Klotz Benol (pronounced "bean
oil") and found it on eBay as well as a local motorcycle dealer (same price as eBay). Klotz Benol is a castor
oil based 2-cycle lubricant pretty much identical to the Castrol product and has an additive to improve exhaust smell. I bought 2 pints and added 8 ounces to a fresh 20 gallon tank of premium gas. The Benol actually did make the exhaust smell a lot more "palatable" and my clothing did smell better. It may be my imagination but I also thought the engine ran a little smoother at idle. In my opinion, the Benol DID make a noticeable difference and ended up costing approximately $6.00 per tank of fuel.
At the next fill up I decided to try something different in order to persuade the little woman to ride in the Cobra so I bought a bottle of Manhattan
Oil Cotton Candy fragrance (the vendor's suggestion as the most popular fragrance he sells) and added it to a new 20 gallon fill. "Hey Mikey, she LIKED it." The exhaust smell was definitely improved to the point my woman liked it and asked me to take her for a ride. The smell was definitely cotton candy but not overpowering at all, just enough that clothing didn't have an objectionable combustion smell after a long drive. Cost per bottle approximately $10.00 so it ended up being almost twice as expensive as the Benol but well worth the effort in order to get HER to ride in the car with me all afternoon.
Thanks again to everyone who made suggestions. I hope this update provides some useful information for many of you. Cheers.