Will they charge less than $105 if it takes less than an hour to do the dyno runs? Just about all dyno shops I have ever heard of charge only in hour increments. If they do the same, it might be worthwhile to use the hour for a little tuning. As for checking P-V clearance, I recommend using modeling clay and not Play-Doh. Play-Doh has some memory to it and as a result is not very stable. It also shrinks as it dries.