It would be a 1968 6000. The info I'll get to you will have everything for that year bike. I have the same. 1969 was the year swap to mag wheels and fold down handlebars. Early 69 bikes had a plate/fold down set up that was mounted on top of the top triple tree. ( basically two top plates). At some point they made it into one. Hard to pin down when that happened. 68 rear swing arm was different than 69. It should have a flat plate on it with slots for the brake and the adjuster plate. Chain guards for 68 and 69 were the same with the Briggs.
By any chance does your 5 HP have a small L bracket mounted to one of the breather screws? I need to make a repo for mine.
Will be in touch,
Regards,
Joe