In 1970 they had the tiny red warning light on top of the control box.----Nobody can look at the control box all day.----In 1971 they installed the horn.
Ignition parts is the least of worry.----Those gearcases are NOT robust in my opinion.----Ask seller about gearcase maintenance history.----Do a compression test.
Given the thermostat location it is between a 1987 and a 1992 model.-----But I think that mess of a corroded motor needs a complete teardown and inspection.----It might even be hard to get all the bolts out.
These units are not robust !!----Gears / bearings on a 28 / 33 HP in the 60's were heftier than the needle bearings and teeth in these 40 / 50 HP ( propshaft rated ) motors.
These gears need to be shimmed for proper mesh.----Shims are clearly shown in parts books.-----Dealer has a shimming kit and can do the driveshaft / pinion gear in minutes.----Good luck with it.