The hfe of the transistors should be around 70 for Q1 and 2, and 100 for Q3 (according to Fuzz Central). I've personally had good luck with some Russian MP38a transistors. You can also build the Marshall Supa Fuzz with this layout by making the following substitutions:
- Increase both 4.7µ capacitors to 10µ
- Reduce the 100k resistor going from the base of Q1 to ground to 10k
- Reduce the 100k resistor going from 9v to the collector of Q2 to 47k
You can also use this layout to make the original positive ground effect using PNP transistor by just inverting any polarized components (basically just flip around the 3 electrolytic caps and diode).