Let's begin with the assumption that we want a variant of High Guard that favors a milieu similar to the Imperium we see: dreadnoughts and so forth. Thoughts on accomplishing that?
Meson screens
In addition to their usual role, they act as armor against meson fire, reducing the quantity of mesons that penetrate on a successful hit to reduce the number of extra hits by spinals by 1 per screen rating; meson spinals still get a minimum of 2 rolls, assuming they hit and penetrate.
Computers
Eliminate the EP requirement (more or less in line with their treatment in MegaTrav).
Eliminate the ship-size limit. (same comment)
Meson screens
In addition to their usual role, they act as armor against meson fire, reducing the quantity of mesons that penetrate on a successful hit to reduce the number of extra hits by spinals by 1 per screen rating; meson spinals still get a minimum of 2 rolls, assuming they hit and penetrate.
Computers
Eliminate the EP requirement (more or less in line with their treatment in MegaTrav).
Eliminate the ship-size limit. (same comment)