This is an often talked about topic. You could probably search for more info. But, ideally, you want lower voltage types, like 100volts, maybe even lower if your rails on the SOZ are low voltage. The reason for using lower voltage types is a better distortion figure. Look for high wattage dissipation and high current capability. Better than 10 amps would be good. This ensures longer life.
Case type plays a roll too. Metal cans are good TO-3 or TO-247's. The TO-220's usually dissipate less, but are good for lower power apps. For the SOZ, it's best to stick w/ TO-3's or TO-247's
You proabaly know most if this.
Most are over kill, I checked all at WWW.DIGI-KEY.COM. The IRFP254 is probably your best bet. It will definitely work.
Sorry, I don't write thread for substitutes IRFP240 My thread is the ID=700MA,VGS<0.1V,the best VGS<0.01, So I use
IRFP250, I buy 20 IRFP250,the VGS from 3.93V-4.54V,
I control VGS difference at 0.04V.