Easiest improvement would be to import two of the better 1600w conical electros that Mytee use , Larry cob supply sells the 240v version , they would also be around 7amps .
Then convert it to a two cord , one 7amp vac + you pump one cord 1 , the second vac on cord two .
That manifold looks very specific to a 5.7 vac , so you would have major work converting the machine to 8.4 . Also the 240v 8.4 is very costly inmost places . I would use the 6.6 insted if u go that route , easier to fit ,any by my own testing performance is the same as the 8.4 . at least the 240v versions .