Even these are hard to find. I bought my '67 without an engine and looked for a CH block for years. And when I say years, I mean a decade. Never found one that hadn't been windowed in a hole or in the side of the block. Settled for a '66 casting block cast before my car's SPD that was apparently an over the counter replacement as the pan rail is not stamped and the only stamping on the distributor pad is the "WT".