I got some back in the early 80's that collided on the block and oil pan bad enough to keep the flange from sealing on the exhaust ports so I called the company which said they didn't know of any problems but 3 sets later they claimed the jig had been changed and I ended up having a nice fitting set. Then a few year later I bought a set that had never been used for $25 at a swap and the holes drilled about 3/8" low on the port flange so they got welded closed and redrilled.
Mitch