Question on a 78 pu

[BigTerry]

I have a friend with a 1978 chev truck wit a v8. He having big problem with it.. He drove off into a ditch full of water.. So far we drain the crank case added fresh oil.. Pull the plugs flipped the motor to make sure there was no water in cyl. Trying the truck won't fired up.. My friend and his brother did a spark plug check to see if they were getting fire.. They told me the spark was very weak.. He replaced the coil.. Spark look better much better.. Well no start.. He has bypass the ignition switch because the housing was toast! The truck has been running since he did that.. My ideas of what wrong is the starter solenoid is bad .. I thinking that there two circuit a start circuit and a run circuit! Right? My thinking is that the solenoid is shorting out the run circuit.. Is this correct on my thinking on why is not running? I haven't mess with a electrical on any trucks since the late 90's he need help real bad he on ssi so he cannot afford to buy another truck.. Thanks guy for any info we can use!