The only two leak sources mentioned that actually could get on the manifold are the valve cover and maybe the rear seal if it could miraculously spray out of the bell housing and get on the lower manifold. But the valve cover seal is right above the manifold and is likely the culprit, especially if the PCV is clogged and pressurizing the crankcase.

I would start with the PCV valve, it's only like 4 bucks. You can find it just between the intake manifold and the firewall on a 351w. It's in a hose above the valve cover. Hope your wife gets well!