You are correct and many of us learned the same way you are.
There are many variables, but you know approximately what your compression ratio will be.
The performance won't be disappointing with 10.5 compression or roughly that.
Your choice of parts are not that bad. I would honestly rather have a little too much compression than not enough. That's when performance will be disappointing.
Plus you will have an excuse to pump some good heads on it if it doesn't run on pump fuel.
It would run fine on pump fuel with aluminum heads.