I suggest...
Check the timing. Take the dist cap off and remove no 1 spark plug. Turn the engine by hand with a wrench on the damper bolt with your finger on the no 1 plug hole. When you feel air pressure you are approaching tdc on no 1 for the firing stroke. From there, set it up on tdc to the mark with the balancer. Then check that the dist rotor is pointing toward no1 plug position on the cap. Adjust as needed to get it close. Yes, loosen the dist hold down bolt with a 1/2 in wrench and turn the dist body. This should get it to start and run, so you can set it with a light later.
Get that right, make sure the carb has gas, and it should start. To check spark, put a timing light on either no 1 plug wire, the coil wire, etc to see if it is firing. I use starting fluid spray to urge hard starters to fire up also.
A note, No 1 on a Ford V8 is the front pass side cylinder, and 1,2, 3 and 4 are on pass side, the rest are on the driver side. Make sure you get the correct firing order for a 78 351, as there are two orders used for 302's. I don't remember what they are at this minute. It should be cast into the intake in the front or side of the intake.