So you can't. There are cert stores, new protocols and ciphers, and eventually u patched zero days.

I know this because I've been playing with a g3 powerboat and all the browsers at this point are no longer maintained to support the above things as of last year. The last person working on it gave up

Called palemoon, except version freeze is much older.

Anything else will goatsy your computer to all forms of zero days.