H or I beams? Keep the rpms down and it will last. Some guys run in the 8's stock windsor block 7k plus rpms. My brother had a shitty eagle kit and it lasted 5 years until he put the 4.56 in it. Went from 6800 rpms to 7500 at the traps. Last 3 passes.
Food for thought, I have stock 302 block, stock crank and rods. I hit mine with 175 and have about 15 passes on it. I have my tune safe and I shift at 6200.
C16 and some -11 plugs is about as safe as it gets but I doubt it needs those just yet. I would try a -9 at least. Pull 3 degrees and see how it runs. It'll work really well if you are over geared or your converter is too tight. Goodluck!