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Well that ain't good.

You appear to have no ground let alone no biasing so first things first is to find out why, does that meter of yours have a continuity setting? (Usually it'll be on the diode setting and be a little o))) symbol) If so, check pin 4 of each chips connection to the enclosure.

However, looking at your photos, it looks like the jacks aren't properly attached to the enclosure, if you were using the enclosure as ground and they weren't in good contact those readings will be incorrect and you need to take them again with a proper ground.

You should expect to see 0V on pin 4 of the 741 & 4558.

OK will reattach and remeasure. I'm measuring from the top of the board looking dow at the IC chip. Should I be doing it from bottom? Tried and could hard get any readings...

Updated with new things secured down. I did not that the battery clip red wire broke off, and that it had been previously soldered to the 9v jack. Does this matter if I'm powering through the 9v jack?

741:
1: 8.78
2: 8.37
3: 8.94
4: 9.26
5: 0
6: 8.81
7: 9.39
8: 0

4558:
1: 8.90
2: 8.89
3: 9.25
4: 9.32
5: 8.89
6: 8.89
7: 8.92
8: 9.39

9 volts for everybody!

9 volts for everybody is bad, very bad.

Possible diagnoses, there's a short somewhere, bad solder joints, broken trace(s) or both opamps be dead.

I would start with bad solder joints, as long as you're half decent with your soldering iron just re-heat/flow all the joints adding a tiny bit of extra (leaded) solder as necessary until all the joints look nice 'n' shiny, after which check the voltages again, you want to see approximately;
9V at pin 7 of the 741 and Pin 8 of the 4558
0V at pin 4 of the 741 and Pin 4 of the 4558
4.5V at pins 1, 2, 3, 5, 6 & 7 of the 4558
5V at pins 2, 3 & 6 of the 741

If you still don't have that follow re-flowing by looking for broken traces (kinda looks like one was fixed already with that bit of wire but i'm not sure if that's an in house hack for the tone bypass) using your meters continuity setting assuming it has one and tracing through the schematic.

After all that you can start to consider the possibility that something in the muffs life killed both the opamps.

Hmmm hang on... do you know if the wiring has been re-soldered at any time? Hard to tell in the photos but i'm not sure it's wired up right looking at them.

Brandon mentioned someone may have modded it before him. Things that are obviously different: some resistors replaced, tonebypass thing is... well bypassed.

Will take better pics, thanks for helping, btw!

fuk, now I'm not getting any readings on any pins...

may end up paying an ILFer to troubleshoot it for me so I don't fuck it up irrevocably

Apologies on the marginal necro-post. Did you ever get this sorted? Pin 4 of the 4558 should read 0, as in electrically attached directly to ground plane. No short will put a readable 9 volts on earth, you've got an open conductor (also appears to be impacting the two voltage splitters that bias the ICs).