Chassis Paint Question.

[CTWV50]

I've zinc sprayed most of my chassis and it's welds. Bought Epoxy Mastic 121 Chassis kit (2ltrs) from rustbuster for the top coat. I then want to use a brushable seam sealer, but I haven't foound a black one so will need to overpaint it. Thinking of just using a tin of black gloss any recommendations or anyone know of a black seam sealer?

Been advised that the 121 stuff will pull away from the seam sealer.