i just wanted to know if anyone knows of someone in brisbane who can put disc brakes on my ute

You can! Read the tech section, go buy some struts and tools then fit some.

very simple to do. Just buy the struts first either 1200 coupe discs, Stanza front(need extra bit too, not as easy) 120y front with discs or a 1200 that was optioned with discs.
I can help if you really get stuck.

i doubt any brake place will do it, they stay well clear of modified brake systems

and for similar reasons mechanics wouldnt want to either, in fact even if you found a place that modifies cars they will want it to be all engineered

which is crap really for the bolt on options available to you, hence being one thousand times easier and cheaper to do it yourself,

check out other threads for options

I'm trying something that may work also:
280zx struts, wildwood dynalite 4 pot calipers, and an adaptor bracket.

still collecting parts, so I don't know how well it works, but the brakes are good for a car 2x as heavy and 2.5x more HP.

It also seems to be about the same price as getting remanufactured 280zx calipers.

my concern is becoming how heavy is all that stuff? my rims are heavy and i have heavy lug adaptors. How bad is unsprung weight really?

What the other guys are saying is correct..... It's pretty easy to do yourself.
If you're not keen I know a bloke that can do some 180sx / Silvia brakes onto your 1200 struts.
PM me if you want his details.

If unsprung mass was unimportant, then F1 racers would have nice strong [& cheap] steel suspension components & the brakes would be at the wheel where they would be easy to service.

The greater the diference between sprung mass & unsprung mass, the better the ride & handling. Reducing suspension weight is, overall, better than increasing car weight.