XR Hunter has it wrapped up for you. Myself and couple of mates hunted hard in the central plateau right through the 80's and into the 90's. We had a mix of bikes - '78 Suzy Mudbug, Ag 175, Ag200 (4 stroke and monoshock), and XR250.
Some of the longer, steeper faces were beyond my Ag175 and the Mudbug due to being so low-geared and we had to walk them up in 1st or 2nd cog - the AG200 and the XR always made it up.
The Ags with their enclosed chain covers were great as that Central Plateau dirt when wet is just grinding past being mostly pumice, the XR and Mudgbug sprockets wore out.
The carriers on the Ags and Mudbug are great, (strong and roomy) but the XR's original ones were too small and needed carriers made up.
The XR seat height is quite a bit higher making solid contact with the ground on the low side impossible - some of the trickier going bits with a deer (or two) on board kicked in the pucker-factor when the point of balance went all pie-shaped

The Ags and the Mudbug seats are nice and low which allows the "outriggers" good ground contact (most times).
Good "socks" over the bark-busters on the Ags saved the hands from freezing in winter and prevented cables tangling with scrub.
You learned quick to be minimalist with gear when using a relatively small horse-power no storage-room bike with all power and space needed for transporting deer.
A good headlights is essential as bike front wheels rarely face where you need the light to face

A tyre pando was a great piece of kit too.
A decent skid-lid is a must too - barrels really hurt when smacking you in the back of the head when (not if) you come off.
Take care of how your sling positions the rifle if you carry it across your back - that (expensive and zeroed) scope might "bounce" on the carrier.
Have a thought about how to get out from under the bike when its super-hot exhaust is burning into your inner thigh when you come off and a heavy stag strapped on board is resisting your pathetic attempts to slide out

That said, bikes open up a whole lot more country to you - especially in recovering animals (or these days just meat).