Ive never had anything crusty enough to feel the need to chase or run a tap down anything and its never caused me a problem. I will spend 2-3 hours cleaning a block after the machine work is done and use a good SS brush in all holes. Brake clean each hole and blow them out then after the 2-3 hours do the finial big soapy wash. So myself have never seen the need to chase every thread, hole, ect.

If you just spent $1700 on manchine work on a block Id hope the shop might of done this already if it was needed.