You can also do a straight up DCF analysis on
http://www.gurufocus.com/fair_value_dcf.phpJust make sure to adjust the starting earnings/share for the 31.6m (56.5% of the total reported figures in the supplement). Also I'm not sure if one should use FFO or NOI as the starting figure.
My assumptions where a requirement of 2x the rate of return on the anticipated 30 year bond. Currently it's 2.2% and I assumed it will be 4.5-5% and that you demand 9-10% as the cap rate.
Another assumption you'll have to make is what you see as the ultimate base rent per square foot and the time to achieve that. It's a decent clip...So far, they are 'mining' in place Sears base rents to non-Sears at a run-rate of about 10.6% per year.
While the large amount of square footage does suggest quite a bit of un-mined potential, just like in a gold mine, you have proved reserves and probable+inferred reserves. I would say that a % of the total square footage is probable+inferred. If you use the Pareto principle, there will always be 20% of anything that you might want to cut out as being largely unproductive. Not sure if their square footage includes parking space and auto centers and those might be considered last or much later in the development process. First they are going after the gold nuggets just lying around on the ground

(Btw, using those assumptions above gets you at or above current market price. But I see it much simpler. If redevelopment return is 12% and DCF shows a number even 1 cent higher than today's price with a cap rate of 9-10%, then you are going to get your 10-12% return.
The 4 variables you might want to answer are,
-will base rents be higher in 10 years by a factor of at least 2.
-will a recession increase your return greater than 12% by waiting for said recession and consequent drop in price.
-will the long bond experience a freak inflation accident and go above 5% in the next decade.
-will SRG require more dilutive capital/debt due to a recession or over budget costs.)