Mr.
There is to date no pressure data that has been made available as far as I know. Marty designed the round to be held at 35K PSI out of deference to the bolt. And what we have are numbers generated from Ballistic software that generates the theoretical pressure for most of the loads that are out there. In reality, when we reload, we try and use conventional brass indicators to help us decide whether we are over the line. Again in reality, these pressures signs, like flattened primers, case head expansion and brass markings are in and of themselves not good. The bottom line to be safe is to use the published numbers that are out there, especially those from Marty as the real world has shown that these are safe, in as much as broken bolts are concerned.
There have been countless thousands of safe 458 rounds sent down range with these numbers, and the only time anyone has had significant problems (two I think, but perhaps just one) was when they went way beyond published. This round is basically still a wildcat, technically speaking from the SAAMI standpoint, but it is very easy to work with.
As to your trajectory query, you can easily do this for yourself with one of the many on-line calculators with the velocity and bullet BC. Or if you have any books, just look to the 45-70 data with the appropriate velocity. For my gun, with a 2.75" scope height and a few of the 300 grain bullets, I am usually (with a 100 zero) right around 5 moa at 200, and 12 at 300.
Craig