If you want HMPKs, I suggest getting a pair of HMPK - easier, faster and cheaper in reaching your goal.
That guy has quite a few flaws, but is breed worthy. When working with dragons, watch the eyes. That guy's eye is almost covered with dragon feature which will blind him. If you find those kinds, cross them to non dragon or metallic to reduce the dragon effect.
Look for the best female (form wise) you can find. I believe the female passes on more fin genetics than the male. But sometimes form follows the sexes . . . I mean fry will be formed like dad while female fry will be more like mom . . . . it all depends on which genetic make up survived to adult.
Look out for dorsal form. Fixing dorsal is harder than fixing caudal.