170 & 225 head swap?

Using the gasket sealer may not be a good idea, it depends on the head gasket. Some should be installed with nothing. Also depending on the years involved, and whether auto or standard shift, you might have to or want to use the carb from the 225 engine and the choke t-stat. Most early 170 standard shift engines had a smaller carb the the auto or the 225 engines. Also 66 down used a different throttle linkage.
Reuse the head bolts.