Hi Chris, first question, do you want an excuse for a new engine?
Because if yes, then all replies are a mute point really.
If you don't want to go to that hassle and expense, then a rebuild
is a good option for one of these engines. They are reliable as you have encountered in the past and they are not too expensive to do up. Even cheaper if a lot of the work can be done by yourself.
To the issue though, if you have no fuel at the injector, you will have no start even with the aerostart.
How many hrs has the engine done??
The engine may actually be OK, the hard start could be due to needing an injector and pump overhaul only. Right now's issue is finding why you have no fuel at the injector itself. I think it is good to assume that your mechanic knows what he is doing, so I will stay out of the obviouse. It is essential the injector pump gets a good fuel pressure from the lift pump. It can't lift on it's own and will quickly stop pumping fuel into injectors if it has the slightest vacum OR, an airbubble that it can not purge. These old Fords HAVE to have ALL air bleed out or they simply will not work. So lift pump is essential. However, to test that theory of injector pump working, take a small container of fuel connect it to the IP and hold it up above the IP to maintain a positive head
and then try the engine and see if it pumps to the injectors.
Before you go further into dollars, get your mechanic to do a leakdown test. NOT a Compression
test. CP's tell you nothing other than a number. Leakdown will tell you lots of important info, mainly where the leak is occuring. It maybe that the valves need attention, it maybe that the rings are shot, but if you don't want a new engine hassle, then the remedy to get you up and running could be low cost when compared to a compleate rebuild
Feel free to ask more if you need.