I dont know what vacs it had originally ( as in are they 1200w or 1400w ) if u have two 1400w then u might not notice a massive difference in performance fitting 1600w vacs , but every little helps .
options ... 5.7 straight swap , two HD (1600w ) electro vacs from the likes of alltec , restormate or others , about 140 each i think .... or if u are fussy about keeping below the 13amp plug rating then fit one 1600w and one 1200w electro .
The 6.6 vacs from woodbridge ( worldwide cleaning support ) at £100 are far too tempting a price to pass also ,considering other suppliers are charging about up to 200 per 6.6 . ( the UK wholesale on the 6.6 by the way is £56 , even so , selling at 100 id say woodbridge dont even stock them , the wholesaler ( maddocks ) offer a service to ship direct to the customer with a custom label attached .
anyway ... they should but u will have to modify the mounting bits in some way and as i dont know the machine , i cant help you
the 5.7 would be an easy option .