The 2N5133's may be a little difficult to source (and as expensive as the ?Lady pro rata), so try every bi-polar NPN you've got in there and stick with the best results. And please don't buy any 2N5133's off eBay unless they guarantee gain around 500-700 hfe. These have already been cherry picked to death so you'll pay a lot of money for a transistor with nothing like enough gain to sound amazing in a muff.
Info from the Muff Master himself (that sounds sooooo wrong):
Skreddy Pedals™ ? Lady:
Thick and huge-sounding, this 1973-era-based fuzz is fat on chords and riffs and soars with infinite sustain on single-note runs. Much more corpulent and "vintagey" sounding than a typical muff--it's got a bit of 60's flavor added in.
Has a wide useable tonal range with a rich midrange and an aggressive, fuzzy breakup..
Sounds like a vintage fuzz feeding a cranked up vintage amp, with as much output volume as you could ever want.