Reaming a longer throat means you can seat the bullets longer, that is until the magazine length limits that idea. You can still ream longer than the magazine but that just means the bullets loaded to fit your magazines will have further to jump before engaging the lands. Target Rifle shooters prefer short jumps-to-lands as it enhances accuracy so there's no point in reaming a throat longer than your magazines will allow.
I use the ballistics program Quickload and manufacturer tables to supplement the usual check of flattening of primers to give an idea of the peak chamber pressure. I recommend starting 10% below recommended and working up slowly. Every chamber is unique and minute differences in internal diameter of the lands will make a big difference in the starting friction, and pressure profile as the bullet starts moving.
There's every chance your peak pressure will be higher with a shorter throat (all other things being equal).
I use the ballistics program Quickload and manufacturer tables to supplement the usual check of flattening of primers to give an idea of the peak chamber pressure. I recommend starting 10% below recommended and working up slowly. Every chamber is unique and minute differences in internal diameter of the lands will make a big difference in the starting friction, and pressure profile as the bullet starts moving.
There's every chance your peak pressure will be higher with a shorter throat (all other things being equal).