Below is a post I wrote on, with info about installing a head. It has pics of sealing products, for the head, and head bolts. My post is part way down the page.
viewtopic.php?f=1&t=102322&start=45
The head could be warped some, and not flat on the bottom side, they need checking when the engine is apart, and made flat at an engine shop, if not flat.
The top surface of the block should be checked too, to be sure it is flat.
It is a good idea to retorque the head, it should be done after running it for a few heat up, and cool down cycles.
IH said to do it after the first 50 hours for a new tractor, or installing a new head gasket, in the newer Cub owner's manuals. If you are having a leak, it could be done before that.
Below are pages from the 1965 Cub owner's manual with the info.
http://farmallcub.com/rudi_cub/www.clea ... age-71.jpg
http://farmallcub.com/rudi_cub/www.clea ... age-41.jpg
