The decals are for the 1976 model year.----What HP is this motor ?-----No chokes , as it appears to have an enricher unit.---serial # makes it 1985 for a 175 or 1982 for 200 HP near as I can tell.
There are score marks on the cylinder walls.----Pistons are likely scored as well.----This motor can / will run.-----But it should be taken apart for proper repairs.----Little bit of carbon on pistons is normal and causes no harm.
Have the battery load tested.----Often a free service.----Then take a 12" jumper wire from battery post on solenoid to small terminal ( not the ground ) on the solenoid.----Report exactly what happens.
????---The key switch applies 12 volts to the solenoid.----The other small terminal off the solenoid goes to ground.----The solenoid connects battery to the starter.----This should be so easy to trouble shoot !