Lead was removed from petrol here in 87 or there abouts. It did lead to valve recession in heads in older cars. Lowered the octane as well causing pinging in higher compression engines.
There are lead additives you can buy to put in fuel. The best thing was to have hardened valve seats put in the heads and buy the higher octane fuel if you had a pinging issue.
If you don't have a higher compression ratio you won't gain anything from higher octane. But.... Don't use lower octane to premix two stroke fuel and not use it straight away.
Haven't heard of the zinc in oil thing?