170 & 225 head swap?

Yea you need all the correct hardware for the manifolds and they need to be torqued correctly See here http://slantsix.org/articles/Slant_...n/Slant_Six_Exhaust_Manifold_Installation.htm

The only other issue is depending on the year of the heads you may have to change the water temp sender 63 and before use a different thread than 64 and up.