You will struggle to find 27 inch legs in Australia.
The only place that is reproducing Gottlieb legs are Pinball Resource. They are cheap, but shipping is the killer.
All GTB EMs prior to (but not including) Spirit of 76 have 31 inch legs - non ribbed.
Some system 80s have a combination on 27 inch in the front and 31 inch in the rear.
If you are thinking of doing a "Ground up" resto on a classic Gottlieb, you will need the repro legs. Some advice on the legs - If you order from PBR, buy 4 sets - as it is the same shipping price as one set - via UPS. From memory US$150 for the box, and it can hold 16 legs. Last time I ordered legs, I ordered 7 sets !