I personally have used my cometic head gaskets 3 times. I was advised by local shop to keep gaskets matched to side they were removed from,clean them with fresh mineral spirits each time, use air gun to blow off any residual and let dry. Before reapplication spray generously with copper gasket sealant. This has been done on my eddy headed 340 with no problems. This was done to have heads milled, and also had to pull them again for push rod clearance when I went to roller cam. I wont try a 4th time but have had perfect results with 3. Hope this helps.