Sleeving the hole like Ron mentioned is the permanent fix for that head.
If it is from the head bolt holes.
If you need it back together and it's from the head bolt holes, I would use "right stuff".
It's a newer "brand name" (Permatex product I think, ? ) and it seems to seal in a less perfect environment than the various forms of RTV seem to.
I get mine form any of the 3 national parts stores (O'Reileys, NAPA and CarQuest).
See it here:
http://www.permatex.com/brand_right_stuff.htmIt can be a mite pricey, it might be cheaper to find some stainless tube and sleeve the hole, if it's just 2 of them.
If you can plug off the water connections to and from the engine a bicycle pump can be used to pressurise the engine; if it's assembled.
Be carefull if you use another source of air than something human powered (ie an air compressor) as somewhere above your system operating pressure (whatever the cap is rated for) it can spit a freeze plug out (possibly at high speed
).
Good Luck.