
For vehicles originally with a weight over 1100 kg, (L Series squeaks by)
you can go to a 5.3L naturally aspirated
or a 3.something L turbo/forced-air/boosted motor.
For vehicles originally under 1100kg (Brumby's for sure)
you can go with a naturally aspirated motor up to 3.something L;
basically any naturally aspirated Subaru motor but their biggest 6 cylinder motor?
Or you can go to 2.something with boost
There is a catch though...
You need to make sure that whatever motor you swap in,
the brakes that came with that motor, or equivalent in braking force
go into what you put the motor into.
Ditto for the differential type and size. Doesn't have to be the same ratio though.
I talked about using my L Series 4wd manual trans with an EJ and he said there's no drama's there, as long as it fits.
Also about tyre size:
Until you go up to 50mm diameter over the vehicle's placarded tyre you don't need to perform a braking test.
I'm lucky that my tyres are only 40 mm taller than original equipment.
I still want bigger tyres for offroad, but maybe I'd be fine if swap them the for day I'm going offroad.
But yes, bigger is 100% roadworthy as long as you book (and pass

Final Drive swapping?
As long as it is done right, sounds okay and isn't obvious at the speedo then its probably fine.
