Hopefully one of the sgplot experts can give you an answer.
But, if you can't find a way to do it in sgplot, you might give gplot a try - you can specify a length (in inches) in the axis statements, and it will generally try to honor that (thereby giving you a way to keep the axes & your plot proportional).
As an example, below is the code for a "spiral" time-series plot - I wanted to keep the 2 axes proportional (whether title statements got added, etc) so that the spiral would not look "squished".
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http://robslink.com/SAS/democd46/spiral_info.htm
Message was edited by: Robert Allison @ SAS
Message was edited by: Robert Allison @ SAS