Re: valve seals
Depending what you have available you need to remove the heads..
Otherwise you can use a compressed air attachment & screw it into the sparkplug hole.
with about 100kpa therebouts it'll hold the valves in the head whilst you compress the springs & remove the collets. Remove the spring, pry the old seal out & replace with a new one, sometimes they need to be tapped on squarely.
In my opinion you cant go past Teflon seals, last for ever (nearly)
Its really not hard to do mate you just need TOOLS
FORD.... "POWER TO THE PEOPLE"...
Member of the "TKTDSGM " Group..