The 75 8valve has turned to gold. Price in the UK for an original used engine out of a car
with shipping is 4731BUP which $9,107 AUD.
You would have to add a few more pennies to refresh the engine of course.
Like wow man !
... and yet you can find a whole car for much less, if you're patient.
Perhaps..
There is a 75 on Gumtree. $10,000 and it's 2.5 V6 https://www.gumtree.com.au/s-ad/hawthorn/cars-vans-utes/1987-alfa-romeo-75-2-5-manual-sedan/1315593413
Allegedly some at the Thomastown Wreckers. Some ads are very old and not removed.
There are some on Classic Car Trader Starting at $29,000 plus for left hand drive cars so that means importation cost on top..https://www.classic-trader.com/au/cars/search/alfa-romeo/75
my105.com site says: "We don't have any Alfa Romeo 75 cars for sale in Australia for sale right now"
car sales do not even has a listing for it.
I am just saying as I see it. If you spot one, by all means snap up the investment.