GM 3.5 L5 Atlas engine

Does anyone know of a shop that has experience doing head work on GM 5cyl engines? I have only found one guy in Michigan who has experience but he has a full work load and will be turning people away soon. His quote was $1,350 which I have no idea if that is low or high. It's for decking it, port and polish, bigger valves and redoing the valve seats. Also heavier valve springs would be put on which is a weak point in those engines. I know the other year people were starting to do stuff with the 4.2 inline 6 from GM which is from the same engine family. The pictures attached is work he did on a GM 4.2 inline 6.