I think what I’ll do be sure it is phased correctly like you’re saying is drill a whole in the old cap at the number 5 post and make sure the spark is straight and not jumping at an angle. I guess that would solve any maybe’s
If you were able to get the CMP <> CKP reading within +1° then you should be all set there.
If it helps here's a picture of how all this lines up inside the distributor cap:
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Moving on to the Vortec
crap crab cap failures, I've attached a photo of what that
looks like when it's bad enough to prevent one of these engines from starting.
(This seems to be a popular failure footprint. The solution is to only use the
very best Vortec cap that's for sale. NOTE: There is a favorite brand in here, just
search around a bit for the current answer.)
Finally, the 13-tooth gear count on the distributor shaft means that it can
be installed 180° out, which leads to the P1345 can't be cleared because one tooth
is too far in 1 direction, while the adjacent tooth is too far in the other direction.
But being within +1° you should be all set. And now just make sure that your cap
didn't arc-over and burn out between the center electrode and the path for the
#3 cylinder.
Best of luck --