That will take a special lens to get a 9ft high image with a 3-4 ft throw distance. Your best bet is going to seek out a projector provider that specializes in that. There could be some information for you at www.projectorcentral.com
. They have throw vs image size calculators. It may take two at each location to get that height.
After you decide on how many projectors it will require then you will need a video wall controller like this:
Video Wall Controller
. You can google "video wall controller" for more ideas.
If you have a good A/V supplier in your area, I would seek them out. Good luck.