modified standardize testing

I have a son with LD in reading, due to processing speed deficit. He scores quite well in other cognitive areas. His reading comprehension is well above grade level. However, he scored basic on last years PSSA (Pennsylvania standardized testing) in reading. The school has recommended that he take a modified test this year to boost his scores. What are the implications of this? Should I insist that he take the regular test with extended time? I think that the school, a cyber school, is concerned primarily with there own scores due to funding issues. What are the implications of this for my child’s future. I honestly think that with the help I am gving him in reading, he will make enough progress to keep up with grade level material.