Unfortunately the Rebrickable paper does'nt seem available at the moment... but anyway I am sorry to tell you that you are moving in a mine field here 
LDraw slopes are kind of wrong since the beginning, they were modeled with a foot that is 4 ldu tall, while real value is closer to 5. And to keep compatibility all new parts are made to fit older ones... and are wrong too.
LDraw slopes are kind of wrong since the beginning, they were modeled with a foot that is 4 ldu tall, while real value is closer to 5. And to keep compatibility all new parts are made to fit older ones... and are wrong too.