At this point in your cars life, no. I wouldn't dump them into a freshly rebuilt engine as preventive maintenance, but you've basically told us that your going to drive it until it dies anyway. I used Stop Leak in my 93 Mustang, which I no longer own, and it cured my cracked radiator just fine. Drove it for another year before I replaced the rad.

If this were my car, I would try and pinpoint the source of the problem. Be certain that its not a simple leak, then spend $350 or so on a new head gasket, intake manifold gasket, timing belt, tensioner, water pump, and hope for a little resale value.