I wouldn't put too much of that on the inside of the cooling system. A little is probably alright but man, I just don't like the idea of putting a goo layer all over the inside of such an important system. I will Jerry rig stuff all day long with the best of them, but I don't mess around with coolant or oil. If that stuff isn't on point at all times, my car isn't ready to leave the garage.
And this is coming from a guy who drove his carbureted 4.6 new edge GT to work today with no hood on, nothing but exhaust manifolds, and the choke closed for 5 miles haha