I just used airroaddirect to get a 400kg diesel to canberra from Bundaberg. It wasnt cheap, but that was due to it being rural and a fair distance. Their customer service wasnt brilliant, but the guy I had was useless, the other staff seem pretty good and fixed his mistakes. So if ya call them and get the guy, hang up and try again.
I hear northline freight are good too, but they were $80 more for what I wanted. I would try both if i were you.
Air road direct: 1300 555 450
Northline: Client Services: 1300 722 534 It should give you the sydney dept.
Just to make it easier for you, for a quote using the largest pallette size, 117W x117L x 50H approx.
Due to the lower weight of the engine, the smaller the pallette the cheaper it will be, the weight wont make any difference unless it weighs more than 190kgs approx. So tell whom ever it is with the engine to use the smallest pallette possible.
Scott