would i have any problem registering a beetle with adjusable front beam?

make sure you have it adjusted at standard ride height & standard cheeese cutter wheels
& maybe no-one will notice!
make it look like an old granny's car!

or I can sell you a cheap standard front end to get it registered with...
I have a few in my yard!

If the welding is to a high standard and the thing is not slammed - standardish ride height, then you will have no problems. Hey if can get a roadworthy, that is what the roadworthy is for.

as long as it passes roadworthy then it can be registered.
Vicroads dont care what you have in it or have done to it.. as long as you have all the correct numbers - engine, chassis etc... and you have a RWC then they will register it.