As bradtx noted the fit is the most important consideration given that you will likely be in the saddle for some time in a tour. I would also suggest loading each up and compare them for load handling and stability. I've seen considerable differences between full touring bikes that I have owned.
I don't think you will find a much more stable bike with a load than a Cannondale. I have 2 ST400 bikes - one is a 1986 very similar to yours and the other is a 1990 with cantilevers and I like them both a lot for their general lightness for a touring bike. The only drawback I see on your Cannondale is the lack of cantilever brakes. I've found the stopping power between my two models to be significant. If you feel the performance of the calipers is sufficient then that shouldn't be a deal breaker.
Do some comparisons to see which is more comfortable for you with and without a load would be my suggestion - right after trying to make room for 2 bikes and keep them both :-)
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Nothing compares to the simple pleasure of a bike ride - JFK