how can you check for block warp
 

is there a way to correctly check your block for warp without pulling the motor and taking it to a machine shop? I used to work on steam and gas turbines and my boss who lives in town has a starret strait edge about 2ft long I was wondering if I could run that along the block and use feeler gauges or would that not be an accurate reading?? three blown head gaskets in a year. smarty tuner, stock head bolts and stock turbo isn't a good idea but I can't put 33k-4k in a 2nd gen swap and studs and this keep happening. it has overheated twice is why I'm worried about the block anyone know the average and max mills that are allowed on a block I found them a while back just don't remember where

You would need to pull head, you can use your straight edge.
If block is warped you would need to pull motor to have milled.