First, make sure the shop has access to a decent tester. Second, make sure teh guy using it knows how to get the most from it. Third, make sure they hand you the written report on it and it contains the info you need. There is a huge difference between equipment and operator. The $300 units are as reliable as a ruler to measure spark plug gap. Most need to be calibrated for the material. Not all iron is the same. The good units calibrate on your specific part. Not a chunk of generic iron supplied witht he tester. Then, there are single point tests, and slide tests. Single point is for that exact spot, it tells you the thickness. It means you need to test all over to get an idea of what's going on there. I test every inch of bore up from the bottom, in the four compass directions. Then there is the slide test. Where the transducer is slid along the surface and takes a fast string of readings (mine is 10 per second). Then when you remove the transducer, it tells you the thinnest reading it encountered. But it doesnt tell you the exact spot. Just that it's "X" thick somewhere. I do the point tests, and then a slide test from bottom to top. So on a typical small block, there are 16 readings of points, and 4 readings of minimum thickness for each hole. I use .150" as minimum possible thickness on the major thrust for a 500+ hp engine. Some go .120, some go .200. All depends. I dont think you will find many factory blocks .200 thick on the major thrusts after overboring. I've never seen one. The thickest I saw has been .198 on one hole, and that same block had .097" thick before boring on the non thrust side. Most fall between .150 and .190 on the major thrust. On any mopar V8, the major thurst is the right side of each bore, when viewed from the rear of the block. So the outside wall of the pass side bank, and the intake valley side wall on the driver's side.