You need to find out from the supplier exactly what toolholders and pullstuds that spindle needs.
BT30 has the same taper as ISO30. So they are similar. The main difference is BT30 toolholders have notches for the drive dogs.
Since BT30 toolholders are usually used for milling machines, they are not always balances for high rpm use, so you need to make sure of that.
Also, pull studs must match the spindle requirement. There are many different types of pull studs than can be used on both ISO30 and BT30, and you need to use the correct ones.