Ampeg heads and resistance, which one to choose?

[Filip Burdon]

I have a question. I wan to buy an ampeg 410hlf and an SVT 3 por or 4pro.

RMS Power Output: 300-Watts x 2/900 (mono-bridged @ 8 Ohms)
RMS Power Output: 490-Watts x 2/1200 (mono-bridged @ 4 Ohms)
RMS Power Output (2 Ohms): 600-Watts x 2
Preamp: Tubes (3 x 12AX7)
Power Amp: Solid State
Tone Controls: 3-Band
Mid Tone Control: 5-Position
Graphic EQ: Yes, 9-Band
Ultra Low/High Boosts: Yes
Balanced Line Out: Yes x 2 Pre/Post with Level
Effects Loop: Yes x 2
Preamp Out/Power Amp In: Yes x 2
Dimensions (W x H x D inches): 19 x 5.6 x 15.5
Weight: 39.5 Pounds

In the 4svt pro specifications it's written that i has 490-Watts x 2/1200 (mono-bridged @ 4 Ohms). My question is what will happen when I will plug one 410hlf to it?
'Cause if i make it bridged it will be 1200watts on 500watt speaker. Can I play on only one cabinet and not bridge it?
If yes what happen with the other 490 watts? ('cause it's 2x490). Is it a problem or can I just use on cabinet and then plug another one when I'll need it?

Sorry if the technical side of question is inccorect I'm a bit newb in those ohms ect :P