The truth be told, I prefer the new chip (NJM2904L). It's a little blurrier (a good quality in a distortion pedal) and seems to take mods a bit better.
IIRC, the 5223 is in pedals made from 2000-2005.
Another thing to keep in mind - you can search for SIP8 equivalent op amps of popular DIP8 ones. The key is that they have an "L" at the end of their designation.
Another option - purchase or construct your own adapter to retrofit a DIP8. Gives you a lot more choices.
Thanks Laurie, I was looking for that thread yesterday. Got to remember to write down the info about the new chip before the thread disappears for me again.