It's been a while. whew. In addition to being place inside a gyroscope to cancel outside to side acceleration and jerk, as in addition allowing for perpetually lying flat, that being what covers die to the side acceleration as Willk.....
With the said arteries being pumped by mechanically enhanced capillary actions, these falling into two families, those being arterial pumps, and literally just replacing the heart with a mechanical heart.
The first, more original, and probably a bit less practical, would be arterial pumps. The capillary action by which blood is squeezed through veins being made more able to convey blood under stress, the natural squeezing and compressing of the veins literally being made stronger and able to convey more blood, with the means of the casings function being something that's plausible enough to not cover.
The second, the significantly less original one, which also happens to be more practical would be the replacement of the largest arterial pump, the heart, being replaced with a better performing mechanical one. This allowing for continuous blood flow to the brain and the body when under high g stress, that being the effect on the human body with regards to high g forces main concern.