How many real lumens does the LT155 put out and how large of a screen are you desiring? Assuming that you can get 15-20 footlamberts, a grey screen such as the Da-Lite High Contrast, Stewart GrayHawk, or perhaps even the new Stewart FireHawk would be your best bet.
You should be able to get very good results with a GrayHawk. I have seen my Sanyo PLV-60 on a large microperforated GrayHawk and it really did improve the image over a flat white sceen. If money is an issue, the Da-Lite High Contrast should also give good results and will cost significantly less.