Hi Tony:
Either speaker will work and both are in stock. The 8" will buy you a little more Bass, they go down to 35 Hz versus 40 Hz of the ACE 640. Power handling is the same. Make sure you purchase the SVC300 for your application. Speaker Placement should be 8 feet apart 3.5' from the 10 foot wall and roughly 5' from the 15 foot wall. 1 pair of speakers will be wired from the the first SVC300 (connected to Speaker A of the AMP200) and another pair of speakers wired from the second SVC300 (connected to the Speaker B) That would take care of two rooms. I am sure you have determined which two pair of speakers will connect to a single SVC300. You can either split the signal after the Volume Control or connect the second pair of speakers to the first pair combining the Input cable from the Volume Control to the cable that will be connected to the second pair of speakers. So the first pair of speakers will have two cables terminated to each input connector (L & R +/-). Make sure you set the Impedance Matching switch to 1/2X. That will get the most output from your AMP200 (connected to your ZONE2 output).
TimL/ 03-6-2020