Yes the older bikes have manual cam chain tensioners. IMO switching from auto to manual would not make a significant difference. And I’m not sure they are a plug and play swap. If your bike has high miles and/or hard use the cam chain could be in need of maintenance or replacement but the auto adjuster shouldn’t really be a problem unless it’s not functioning properly.
I’m guessing you inspected and adjusted the valves. If not, that is more often the source of the noise.