Giving a speaker more than its rated power is seldom bad; you will (or should) hear they can't take it well before they blow, plus most any decent speaker has in-built fuses via means of lightbulbs or real fuses anyway.
It is quite hard to blow a speaker with too much amp power, only happens basically if you go into feedback, and then blow the tweeter. OR really disregard horrible sound and the sight of woofers trying to detach from their enclosures.
What blows fullrange speakers the easiest is too little power.
BECAUSE if you for instance have an amp of 600W and a speaker of 600W both rated that at RMS and 8 ohms for instance, then what happens when the speaker is pushed hard and the voice coil jumps almost out of the magnet with bass hits? Yep, the speaker impedance drops drastically, say down to 2 ohms.
Now there are plenty of amps that may give 600W to 8 ohms OK but maybe only 200W to 2 ohms, and that means that when the speaker impedance drops, the amp cannot provide a clean signal, and instead produces square wave, and THAT blows up the speaker faster than you can say oops.
With Peavey boxes & peavey amps I don't think that'd be much of a problem, but especially if you cannot verify what does the amp yield in low impedances, it's always better to err on the side of a bigger amp.
We used to have 1000W amps into 750W fullranges, and I recall one occasion where we blew a fuse on one of the cabs, or tweeter side actually when it fed back ugly...but it was a Peavey cab and had a lightbulb fuse so it was a 5-minute job to fix it back up.
Dee
"When life's a biatch, be a horny dog"
Amps: Marshall JVM 410H w/ Plexi Cap mod, Choke Mod & Negative Feedback Removal mod, 4x12", Behringer GMX110, Amplitube 3/StealthPedal
Half a dozen custom built/bastardized guitars all with EMG's, mostly 85's, Ibanez Artwood acoustic & Yamaha SGR bass, Epiphone Prophecy SG, Vox Wah, Pitchblack tuner plus assorted pedals, rack gear etc. for home studio use.