Heres what happened with my line which was a hm x traditional pk.
Since trad pk is literally a short finned vt it is the same as crossing a hm to a vt.
In this case the male was carrying pk so luckily pk arrived in the F1.
But all fish had horribly round tails, ranging from vt to delta (some pk were 180 but had trad pk roundness).
I'm still trying to get rid of the round tails, it is the hardest thing to get rid of, even though the tails are now 180 with 4 rays its still too round.
I agree with bambi, if you want nice hm stick with a hmpk or nice hm girl. Stay far far away from anything with a rounded tail, it will become your endless nightmare