that blows. it was hot as hell the two day i was ripping and replacing over. at least i was out of the sun in a garage, but it was still hot as balls.
if your heads are ok dont touch the heads, i only did them cause i top swapped a n/a block. had no choice in the matter.
i'd do the lower conversion kit. a lim gasket kit, upper plenum gasket and new valve cover gaskets. new coolant, oil and a filter.