71 Dart Slant Six w 904 into 64 Valiant

Exactly. Who might know how compatable the newer column and linkage would be. Ya, it might be better to just get the engine. What about the newer crankshaft and the older converter snout? That's an issue on the v8's.
I sell a bushing that fits in the end of the crank (fits the V-8's also) Use the 71 flexplate. Easy/peasy