OK, I'm dumb, need help

This is what I'm looking for! Appreciate all your comments and sense of humor. I am not chasing a horsepower number. Just want to understand the length and breadth of what can be done to a /6. It may be that a mild build is best as far as reliability goes. What is your opinion on early heads (w/ spark plug tubes) and later heads (w/o plug tubes)? I am drawn to this build because it is different and a hi/po /6 sounds incredible.If a person doesn't go all Clifford, what would you change? Thanks for the input.