What is the best way to go about this?

I run a small theatre group and for years we've been looking for somewhere for us and other performers to perform. I was out with a friend the other day, and i came across a practically derilct theatre. the bloke who owns it hasn't bothered with the place for years. However, the guy who owns it has (in the past) always insisted that it be used for a certain charitable cause, and the idea I have for the place doesn't fit in with these idea's of his. But then again, he doesn't use the place and it hasn't been used for about 20 years. I know this is going to be a case of slowly slowly catch a monkey, but have you got any suggestions of how to go about it? I thought of saying that I would invest all of my own money into doing the place up and donating 5% of all net profits to any charity/ cause of his choice, do you think that sounds condecending? I seriously need help!! Thanks