Every class in promoted form has a 60 HP cap, and a 30 cap in everything else.
The notable exceptions are:
Classes promoted from all Armor classes: 70 HP, 35 Def, 25 Res, and 25 Speed caps
Classes promoted from Troubadour: 35 Luck cap
Classes promoted from all Peg Mage classes: 25 Pow, 35 Speed caps
And there may be some cases where units generally cannot hit 30 in some stats due to their bases (or hit their respective stat caps in general: i.e. no promoted Armor unit can get 25 res).