Hi bro,
You got 2 account name leh ?
Anyway, LED is current driven not voltage driven so constant current is very important.
Your formula is correct, 1A * 3V =3W but SSCP4 can go up to 3.75V which meant It's 3~4W LEDs.
For your setup, IMHO...PLN-30-36 is the best bet !
Alternatively, you can look for sherman as he might have spare 1A Power supply driver to sell.
Regards.