two options I see. Easiest is bridged into the mono in on the SVT. You won't push 1600 into the 810 unless you are crazy loud but even if you did, those 100w speakers are around 100 rms/200 peak and the cab would be similar (double rms for peak).
the 500 a side at 8 ohms going into the dual 410 setup is perfectly fine too but slightly more complicated by having the extra cable.
You are maybe
less likely to blow a driver. You'll know you're getting close when the 810 is shaking your flesh off your bones.