I decided to try adding a wide angle lens to enlarge the size. The trick is to find a lens that can be put in front of the current lens that would project an evenly lighted and sharp image...as well as no vignetting. This week I purchased a Sankyo .75 wide angle lens off Ebay to try out and it so far is doing a great job. It has made the image about a third bigger. The picture is sharp with no vignetting.
My original Sankyo Pro Zoom lens did not have threads to attach the 55mm wide angle lens... I glued a 55mm step up ring to the projector lens. This allows me to add and remove the wide angle lens as needed.
Original Lens
w/ .75 wide angle adapter lens