Just for some S&Gs here's some data from the circa 1966 Speer manual #7. The data may not be reliable as the manual price was only $2.95.
But back then ya usually got a little more than ya paid for.
Just for comparison, ok? (most folks think the books limit the loads instead of the rifle) But back when men were steel and ships were wood this is what we worked with.
.280 Remington (ALSO 7mm/06-7mmx64mm
Rifle: Remington Model 725 Cases: Remington
Primers CCI-200 Barrel: 24" Twist: 1-9 1/4
"Heavy loads should be avoided in loading for the Model 740, 742 and 760, consequently loads preceded by (1) should be considered absolute maximum for these rifles."
4831 - 62gr - 3180 FPS
4350 - 58gr - 3235 FPS
4831 - 59gr - 3022 FPS
4350 - 55gr - 3048 FPS
4831 - 58gr - 2888 FPS
4350 - 54gr - 2902 FPS
Subtract maybe 20 FPS/inch of barrel. Ought to be close.
Not much of a bullet selection back then. But the job still got done.
I'd be working on that Scirroco load for sure.