The early official service manual has some great lubrication diagrams in it. They show that the 450 runs oil from the oil pump, through the centrifuge, through the clutch cover, then up through the cylinder casting and head casting via the stud holes on the right side. Because of this, two of the eight acorn nuts atop the studs are sealed using copper washers, while the other six are steel.

All the hand-wringing online about 450 oiling is unfortunate. I was in Honda dealerships when these bikes were new and stayed in dealerships for most of the first 20-plus years I was in the biz. No one back in the day worried about oiling until the forums started to. I have a lot of history with the 450 and have never seen any bad outcome from not waiting "three minutes" before putting it into gear.

That said,

1. Honda did issue a warning about extended periods of idling while on the sidestand. There was even an oil pump pickup production change on the 450.
2. The oil pressure as with all rolling element crankshaft Hondas is fairly low, just as in the Brit twins that inspired the 450.
3. The oil passing from one cam to the other is unfortunately circuitous (seemingly not the best design, resulting in one cam getting oil after the other does).
4. The rocker arms (followers) are prone to failure regardless of how perfect or not lubrication is, due to the cam-to-rocker geometry. Of course, with incorrectly low oil levels the cams and rockers are going to fail on that basis as well.
5. Like all Honda twins owners tend to run these engine out of oil, especially when ridden at high speed for long periods.
6. Virtually no one cleans out the centrifuge regularly.
7. And when they do they sometimes assemble the removable plate and canister wrong, with pinched o-rings and other oversights that can affect lubrication.