venturing to the other side. Need Suggestions

The engine is a 351W out of a later model, mid 80s wagon. Right now it has the original 4 speed that was behind the 289. They were never able to get the 4 speed shifting right. The clutch is at the floor to get it to shift and all the linkage adjustment is used up. He wants to just drop in a C4 and be done with it. He's as stubborn as me so talking him out of the swap is futile.