I'd like to know why it won't work. I know for a fact the big block and slant 6 pump arms WILL interchange. I've not had a need to swap big block for small block arms. I can also tell you big, small block AND slant 6 fuel pumps ALL have the SAME mounting pattern and excluding the pump arms, the pumps will ALL interchange onto each of the engines.....albeit the slant 6 mounts upside down to the rest. The big and small block Chevys also have the same mounting pattern as the Chrysler engines. That's why one fuel pump block off plate fits ALL those different engines. I'm sorry I cannot help with the arm swap question in your situation, but since the slant 6 and big block arms do interchange, I would try it. I'm sure you already know they won't be the same on the engine side, but I believe that's what you're looking for.
