M. Requin

This really sounds like a fuel delivery problem to me, like a Briggs and Stratton running until the carb float bowl is empty because there is crud in the gas tank that only allows a tiny flow rate from the tank to the carb. Have you checked fuel flow per the WSM? I know you just installed new fuel line bits, so this is just a WAG...

Rocinante

I had Rich at 928 Garage change the fuel pump, I'm reasonably confident that he said he would check the fuel system before he did this (I remember him saying something about checking fuel pressure). It ran like a beast a few times after that so I hope that's still not a concern.

It may be hard to tell in the pics below, but the rotor looks spot on with the hash mark. The cam marks looked the same, maybe off 1mm at the most

What should I move on to next?

Mrmerlin

the rotor tip is 180 away from pointing at the hash mark
SO lets start over.
put the engine at TDC.

the crank and cams must line up.

with that done the rotor tip should be pointing centered at the hash mark, in your picture the rotor is 180 degrees out

Rocinante

Got it. Sorry, this is the pic I needed to send you. TDC, rotor pointing at the notch, which is what I'm assuming when you say hash mark.

Mrmerlin

OK that looks like TDC while the cap is off make sure the little fingers are not rubbing this will be evident by seeing orange dust on the fingers

Rocinante

Mrmerlin

OK timing is good.
pull a plug wire off and put a grounded plug into the lead, crank it and check for spark.
good spark? THEN
connect the wire,
spray some ether into the intake and see if it fires.
Result?

Rocinante