Continental O-300 longevity

Can an 0-300 last a long time?

I just bought into a C-172 with an O-300, approx 700 SMOH. It is down
for an annual and we have discovered #2 and #4 cylinders have sticky
valves. One of the valves will need to be replaced.

Surely there is a time-tested set of techniques somewhere on how to
maximize the life of these motors.

We do all the standard things - gentle starting, conservative leaning,
gradual power changes, proper oil changes, minimized idling, fly it
frequently, etc.

What are the "special" things that this motor likes in order to last a
long time? We are wondering about leaning techniques, autogas (it has
the STC but has been using 100LL), valve guide set-up, carb setup,
additives, etc.

Thanks for any info.

P. S. -- Don't tell me about MMO. One of my flying buddies is a
chemical engineer for Shell. MMO is nothing but kerosene and some
other solvent mixed with dye and perfume. Besides, it is illegal. He
suggested that if anyone could not resist putting oil in their gas,
they should put in a slight amount of synthetic 2-stroke oil. It
provides a moderate lube at very thin dilutions and very high temps,..
and it burns very cleanly -- no carbon. Also illegal.