do you mean a slant 6?

if so you can do the old hot rod trick on the 72 slant 6 k-frame.

you use a 72 v-8 driver side engine bracket for the square rubber biscut motor mount.

then use a v-8 truck engine bracket that will use the square rubber motor mount.

this will bolt a SB v-8 into the 67-72 slant 6 k-frame.

truck mount on SB v-8 in a /6 k-frame looks like this on pass side.