Mate,
1987 was a long time ago! I know I was well and truly there, it was a great time of my life. Caught a lot of fish too.
Perhaps it might be time for an upgrade. You'd be amazed how well even a modern 40hp 4stroke would push a 4.3 boat and a lot less stress.
A good 2nd hand modern o/board 50 would go well too! Just a thought but, if you want reliability age will weary them.
Brian.