Not familiar with 1N36a, but I gather it is in the same family as a 1n34a.
In a word, Don't. You will not notice any big improvement by doing this, and from the content of your note, it is entirely possible that you might not possess the soldering chops to come away from this with a pedal that works properly the moment you box it up again (apologies if I underestimate your chops).
The SD-1 provides more gain than the TS-9, and employs a 2+1 diode complement to provide something approximating asymmetrical clipping. Replacing any of the diodes with a germanium type will reduce the amount of headroom provided by the existing diode complement. This will result in more intense clipping at lower drive settings, but also lower output volume. That may not be what you want.
What exactly does the pedal NOT do right now that you want/need it to do?