Are you installing new construction window or a replacement window ( the kind that inserts into the old frame? If the latter the window should install from the inside but
if the former it must go in from the outside. Pre 1978 falls under the lead laws for
window replacement, though homeowners are usually exempt, be sure to take the
protective steps if there are children or pregnant women in the household. Lead is
very dangerous to fetus or children under six. No I am not a fan of the EPA but this
is one area where some common sense should be used.