Outer Limits 4x4 Board

hi can somebody help me with a couple of things:
I recently bought a 2nd hand impco dual fuel setup for my mav and need advice as to someone reasonable in sydney (east/south preferred) to install the kit and certify it.

Whats a rough guess as to costs if i supply all the gear (tank in date etc) ?

Also, i don't have a sub tank so i was hoping just to secure the LPG tank in the back (inside boot) and use the existing petrol tank - is this legal? i don't mind losing the boot space. otherwise i guess im in the market for a sub tank.

I have no tools so can't do it myself, but am keen to install due to crippling fuel bills (as all petrol GQ guys probably have).

Thanks Alot

I had gas fitted to my 80 real neat job but the gas thak went under the car where the sub tank went I have seen them in the boot's of patrol's before so you can do it. My set up cost me $2200 new with the valve oil dripper whitch I recommend you get fitted to It stops you burning valves. hope this helps
Jimbo