Many good motors run in the .035 or even .060 range. 90% of builders want to be in the low 40s. With that being said there are many motors that have record passes with .050 or even .060 so listen and trust your builder and you will be fine. Theres a lot that goes into it but if the pipe works and traps well the motor will like looser squish. Timing, fuel , dome shape, squish band width , velocity, and many other things change the way a builder will want to set em up.