It is a time consuming job so plan on a good number of shop hours. I did mine on my 87 myself. The original O rings get brittle and fail. I replaced the O rings and added Felpro umbrella seals at the valve stem base and it eliminated all oil/valve stem leakage. Chev small blocks are notorious for this due to the way they have gun drilled the holes since 1955. I know as I used to sell Chevy the drills. You can do it with basic tools. Only special tools are a valve spring compressor and you will need compressed air to hold the valves in place while the springs/keepers are off each cylinder or you risk valves dropping down into the cylinder. Not a difficult job--only time consuming.What can I expect to pay to have the valve seals replaced in my 87, thanks Jim.