I've also been considering rebuilding another engine. I thought I understood making an engine more efficient with some of the tricks that performance engines use, but the more I think about it, the more I wonder if that is correct.
Example:
If you polish the back of the valves, and do a 3 or 5 angle valve job, clean up any sharp edges ect, those things are normally done to improve airflow.
More airflow + more fuel = more power.
As to coatings, apparently there are some good ones on the market that are diy. Friction and heat reducing.
I'll thow these out just for sake of discussion:
