The rear's weren't too bad from memory....just disconnect the sway bar, the shocks and the diff breather and unbolt the brake line bracket from the underside of the floorpan and the diff dropped plenty. No need to pull of driveshafts or control arms so a nice quick job.
I used OL in Brookvale to fit mine initially (though I've had them in and out a few times since by myself) but it's fairly safe to say that they know a lot more about Patrols & Cruisers than they do about JK's. I like the guys in there and they always try to help but they're not the best at following instructions....even simple ones!
I'd think Mal at Tyre Power/British & Swedish Motors in Narrabeen would be happy to do it. They have lots of experience in working with solid axle suspension on Land Rovers/Range Rovers (as well as Patrols, 'Cruisers, Suzuki's etc) and have always seemed knowledgable and open minded (which not all garages are when it comes to Jeeps!) when I've both my JK and our Jimny in there for for wheel alignments and bits and pieces. I'd certainly use them over OL if I was doing it again and didn't want to do it myself.
There's also Mitchell Bros is Brookvale who I know have done work on other peoples JK's. The few times I've been in they never really seemed like they wanted to answer my questions but I know other's who've recommended them.
Macquarie 4x4 also do a bit of work on JK's (and one of the guys owns one) but they're a bit further away (Windsor I think).
Not sure if there are any closer to you.
The other thing to remember is you need to torque the bolts up......a lot. I'd guess this was the same on your Grand but the track bar bolts and lower control arm bolts all need to be torqued to 125ft/lb. Not so bad when you working on a hoist but not always easy when you're lying on your back under a car.