The short answer....No. They are similar but different enough to make conversion well nigh impossible. S/A plates can be identified by the two welded in spacer tubes on the left hand plate, with a frame mounting hole just below this. These are absent on the plunger plates, which have a cut out and a separate single spacer at the front/top. This can be substituted with your own fabricated part in the short term.
In searching you may find a pair of plates which look to be exactly what you need but still don't fit....These will turn out to be for the earlier Longstroke A7 engine, which has slightly different positions for the crankcase bolts, but the same frame mounting points.
The plates still turn up on your favourite Online Auction Site and Autojumbles, otherwise its out with the cardboard templates and the 1/4" plate. Usually found a bit bruised and bent, so finding ones ready to fit is a tall order.
Swarfy.
