i personally dont think the aluminum would hold up. mine has been a little rich and i get a ton of condensation, especially in the valve covers and rockers. also i pulled my bowls off to change jets, and after it had sat awhile they were extremely diificult to remove and a white chalky build up was all over them. also signs of moisture in the accelerator pumps.i get good results from the www.raceone85.com board. you might ask around rhere and someone might know more
there is a problem with leaving it exposed (open air) for extended periods of time (carmelizing in the carbs). Race gas will net you the same results (or pump gas if it sits long enough!)- The only time we've seen problems with bare aluminum are when the planes go through massive heat swings (condensation) I have many customers with aluminum fuel cells with no problems for 4 years+ now. You will get some condensation in the valve covers, especially if it doesn't get warmed up like it is supposed to.