What wattage does the Mono Block B head put out at 4 ohms? Maybe 250? If you're going to replace the two Cerwin Vegas, I'd go with two 3015 drivers. The 3015 will be brighter and louder than the 3015LF when driven by a single amp channel, you might not like the mix.
I was thinking that actually about the 3015's. I really like how the Cerwins sound, I'm just worried about blowing them up quickly if I pound them with the amp wide open frequently.
The Monoblock is probably more like 165 or 170w at 4 ohm. It's 320 at 2ohms.
Wired up the 8x10 with new speakers tonight.