Auto to Manual? (Sort of)

First off, What year is the 170 engine? What year is the 225 engine? Makes a difference.
Next, All slant six engines were "drilled" for a pilot bearing, but not all were "reamed" to the finished size.
The size of the center hole in the flywheel/flexplate changed between 1967 and 1968, so you need the flywheel to fit the crank.
If your "new" engine is later then 1967, and the pilot bushing does not fit the hole, you can use the pilot bearing from a Dakota. (or you can ream the crank hole, or have the pilot bushing OD turned down to fit).