K&W block seal

Sold a lot of K&W in the 70's and 80's when I owned a parts store. Had many happy customers that said it worked. But it is all relative to the intial problem. If you knock a hole in the block , it won't work. If you forgot to put the wrist pin clips in your 68 340, it won't work ( found out when we tore it apart later). Head gaskets or small cracks in a head or cylinder, yes it will work.