Big block Chevy. The work is simple. Drain the antifreeze and remove any brackets on the intake, pull the distributor and mark #1 cylinder and remove it. Remove the valve covers and the rockers and push rods. Raise car and remove the exhaust pipes. Remove the exhaust manifolds. Take out all the head bolts and pry the heads off. If an AC car, take off the compressor and move it out of the way. Without knowing what vehicle You have, the instructions are basic. You may have to scrape the head gaskets from the block and sand the surface clean. I pull the drain plugs from the block so no antifreeze runs into the cylinders. Not knowing how many miles on the engine, I would check the ridge on the top of the cylinders. Did You do a compression and leak down test? The machine shop will tell You how bad the heads are. Get a good T square and check the block for trueness. The rings could be worn, depending on how bad the heads are. You might need the heads planed.They will install new guides and seals and check the springs. NICK L72