Wow Effvee, reading from the beginning to this point, one thing thing became very apparent. You never got your original question answered.
Is there anyone that sells a (spray bar) kit for adding a oiling system for the rocker arms and valve stems.
I've been searching for this very thing since 2011 and as of yet
, No.
That said, performance V8 motors often use these, but the lowly flat4 gets none.
As with the progression of time and horsepower this well come to pass that it will be common place, even on our cars somewhere in the future.
Now that I got that out of my system..., you could use a single stage dry sump pump and plumb the pumps pressure side just as stock and the first stage / suction side that would return sucked up oil to your reservoir tank could then be plumbed as a dedicated oil sprayer.
How you go about building this is up to you. But I'd copy the V8 boyz and run an aluminum line inside the valve cover and drill one or two 0.030 holes above each keeper face and spring area. Additionally you could cut this gear set and housing down to 15mm, remember your not feeding pressure to the bearings, just spraying oil. Or the easy way and cut a groove in the cover to be self relieving of to much pressure.
Now Effvee, I build widgets from time to time and I've found it best to close my garage door and just build it no matter what the nay sayers say. So whether theirs a need on someones else's car is not the point..., you want one for your ride, that is the point.
You work out the details and build a kit..., people will buy it. That includes me!
Enjoy the day, dd-ardvark / David