65 Barracuda daily driver
sounds like you should be solid then!
i *know* K-seal works, i've personally used it with no ill effects. i've tried alumaseal and it was dogshit each time, and on teardown inspections, post mortal, it was all just gunked up in the radiator and i wound up having to cover that expense as well.
either way, if you don't need it, don't use it. and if you do need it, think twice about using it!