Do these markings look like poss het??

[SlitherinSisters]

You have nothing to lose doing that. On the bright side if you breed him to a pied(and he isn't het) you will make a bunch of 100% hets, some being pastels. If you get lucky and land a male pastel het for pied, you could breed him to mom the following year to possibly make pastel pieds!!

That would definitely be worth it even if he wasn't a het! Pastel het pieds
He definitely has what looks like pied markers. I say it's worth a shot, you don't lose either way!