My flush plugs missing when I got it.

[Mason Sowell]

My 1974 mercury 7.5 hp model 75 had not a flush plug in it when I bought it. It's just a plug right? If I was to get a pipe plug, there shouldn't be an issue, as for as blocking cooling passages, was thinking of like just the Allen wrench style plug with a tiny dab of Teflon RecTor seal. Wouldn't that work? I never scene the original. Thanks!