Oscilloscope recommendation for 89 Chevy TBI ignition issue

I have a 1989 4wd K5 Blazer 5.7l (SBC 350) TBI throwing intermittent code 42, "EST" (Electronic Spark Timing). I've replaced wires, connectors & parts multiple times but the problem persists. More info here:  ck5.com/forums/threads/intermittent-est-...7l-tbi-700r4.352522/

My question for this forum is which Oscilloscope I should buy to help troubleshoot this issue? My (inexperienced newb) idea is to hook up a USB 4CH Oscilloscope to each of the 4 wires (PPL/WHT Reference, WHT EST, TAN/BLK Bypass, BLK/RED Ground), set the software to "record" the voltages from the 4 probes, drive around until code 42 occurs, stop the "recording" and then review the data to hopefully figure out whats going on.

Looks like a Hantek 1008C should do this? I went back and forth with Cluade but it wasn't sure if the sampling rate and memory depth would be sufficient for what I'm trying to do. There are other models that might help too, like a Hantek 6254BD, 6254BE or 6074BC.

Please let me know if I've posted in the wrong place or if this has been answered elsewhere.

Any help is appreciated, TIA

Any scope with a properly set trigger should be able to catch something.

This might be of some help. 
 

Does setting the "trigger" ensure that data doesn't get rolled-over?

Thanks for reply. I actually bought the paper version of that manual, unfortunately that decision-tree trouble shooting page doesn't apply to intermittent code 42, only steady-on code 42.