Distance has little to do, unfortunatly, with strength. It is true that the touring pros are hitting it longer with strength trainning and they are in the gyms these days. But this is to gain only about 5-10% more. That's all.

What you are talking about here is the difference in 245 vs. 295 and thats about 25%. This kind of difference comes from technique.

So don't worry about the strength as much and work on the fundamentals.

What is probably the most impartant thing you can do if you have the time to work out is streach. Increase your flexability. Especially in the back and shoulders. These are the hardest areas to get loose after driving in a car and the first to get tired at the end of a round. Once your back goes, then your hands and arms take over and you loose control and distance. Flexability will increase distance more then strength. What happens is that you increase the length of your lever-arm, and as that length is added in a centerfugal rotation, the speed at the end of the club is increased. And that is where more force is put on the ball making it go father.