Deano, get a list from SA roads authority of all the engineers available to you. They seem to charge a variety of prices and what you've been quoted is getting up there.
Also buyer beware of Gforce kits, that aren't on Gforce chassis and on toyota crown chassis. Not knocking the crown chassis but the resale value of these are poor and you would not want to pay Gforce chassis price when in fact it's a crown chassis. I came across two of these on my travels, and one seller had no idea.
My 2c, good luck
