Re: 1975 Mercury 1150 or Volvo/penta 1967 BB 70.
Zona, That Merc has a battery powered CDI Ignition systems (no points) with a beltdriven distributor. It is very reliable, however some ignition parts are getting a bit scarce and are pricy. Check the wiring harness on the engine. The insulation is the first to go, but new replacements are plentiful. The distributor and stator wiring can also start ot fail, and to replace the wiring is not posible w/o replacing the component, and this is $$.
The balance of the motor, props, plugs, carb kits etc are very common and easily available.