Nu, my man, you already hold the answer to your plight. Go with your heart and let your wallet follow behind. To me, it's a no-brainer, but first I must ask...which specific model are you looking at? I'm assuming used, but I don't want to assume anything. If it's the PF-410HLF then I think, except for looks, it outta match up pretty decently. If it's an SVT series, then so much the better. Just stick your combo on top and now you possess a 6 X 10 weapon of mass destruction!
Ampeg cabs tend to run, according to the manuals I was just looking at, around 100 dB with one-watt sensitivity. I'd guess your combo would be about the same (no such data provided for the combos) so that means they'll all play about the same level; the combo won't blow away the 410s in volume. Again, let us know what you're looking at and we see how well the fit would be. Most likely it'll be fine.
I'm excited for ya!