Well Aussie, you've probably got a few K's up now, so how's it going?
As said above, it will take a few K's to run everything in and wear a few of the high spots off.
After all of that, (mine took about 2000 K's before I was happy enough to start changing things) and things start to move freely and the nois department settles down, you can start thinking a little more seriously about lubricants.
For what it's worth, I'm of the opinion that engine oil was made for engines, and gear oil was made for gearboxes, hence, I'm fine with a 20 W 50 synthetic in the donk, but why run an engine oil in Primary and gear box when there are way more sophisticated lubricants out there that are made for the job.
I run the Nulon street and track high performance synthetic gear oil in the tranny, find that the 75/90 is doing the trick quite nicely at the moment, may go for the 75/140 during hot summer, will see.
The primary also has special needs with that old tractor chain method of transferring drive, and the clutch plates all in there together.
The compensator and chain need all the protection they can get, so a top end synthetic heavy weight is good, just so long as the friction modifiers are of the type that screw clutch friction plates.
One blend I have had more than pleasing results with is to run the Nulon Synthetic 20 W 50 with 100 mills of the G 70 heavy duty supplement.
Fixes a lot of noises, provides excellent protection for comp and chain but without any detrimental effects on the clutch.
I'm pretty fussy when it comes to how my Harleys run and sound, so have done a fare bit of research on what lubricants I use and it's paid off with sweet sounding donks, primarys, and to some folks amazement, quiet and smooth transmission operation.
It can be achieved.
Good luck Mate, Happy Trails.