Best advice is to come to Club meetings and join if you haven't already. They are on the 1st Sunday of the month at Sanctuary Cove for breakfast. Start at 7:30am. Normally a run afterwards. You will get to see most of the kit types available and get a few different perspective.
Here is my opinion...I hope this comes out right, I'm having a bit of a sick spell at the moment.
I would put at the top of your list Harrison or DRB. They are made up here and as a result you will have more support, knowledge and resources locally to help with build.
So your building a hot rod Cobra...
I prefer fabricated A Arms, others prefer donor like Jag & Torana. Donor can be cheaper, but not as cool I reckon. To be honest they all do the job. Harrison uses fabricated, DRB uses Torana or Jag.
Rear end, well it depends on what you are after. Traditional is Ford 9"(shortened), but these days independent rears like Skyline R32 GTR and more expensive XR8 LSD are popular. I like Skyline, good value and it bolts into Harrison. DRB uses old trusty Jag rear end as does RMC.
Forget LPG, no chance of approval. In QLD we now have 5 year old rule. It basically means with a bit of fudging you can get away with any Ford EFI 302 windsor, newer Ford 4.6lt modular, Holden(chev) LS1 or Lexus 1UZFE 4lt. All have advantages & disadvantages. Lexus normally works out to be the cheapest, buy a Soarer/Crown front cut and use radiator etc and sell the rest. Wreck a falcon and use 302w, T5 etc.
Also be aware of waiting times. I think DRB are well over a year now and boy do they pump them out. Harrison is a lot shorter. With my brother I built a DRB 7 years ago and a Harrison 2 years ago.
Check out "Is it Worth It" thread for some more info and do a search.
Have fun.
Budget 30k+ and that's being very, very tight. So using all 2nd hand stuff and doing everything yourself.
And remember swap meets & trading post are your friend.
