My set-up is using Manton chromoly pushrods and standard Bugpack dual springs.
Did the testing of spring pressure at installed height and all that;
Forgot exactly what the numbers were.
There was plenty of room before coil-bind, so I threw a set of thick shims in there and ran it.
The Bugpacks showed quite a bit more pressure than the standard Scat duals at the time.
My rockers are the China copies of the Autocraft 1.4s.
Latest Rage brand AFAICT.
The roller-bearing type that everyone likes to hate..
(Like Kona does in the add you linked

)
I shimmed them up carefully to keep the oil pressure up in them,
Then filed a small spray groove that points at the lash cap.
Kind of like the 'bulletin' VW put out with the connecting rods in type 4s..
Hoover mods would likely help this a lot.
Can't help but think the VW engineers drilled clear through the stock rockers for a reason.
Plus, with the 'dry side up' using ratio rockers, it can't hurt, right?
Those 1.4s in your add look worth trying.
If they break, you will likely just lose power.
it's not like using a cheap valve or something where catastrophic damage would result, right?
Just approach China parts at a fraction of the cost of the real thing with reasonable expectations/caution...
(I'm brave like that

)
My heads are German 040s with professionally done non-welded 'oval' ports.
Old school artistry by BRE, actually.
The manifolds are ported all the way up.
(to 36 vents BTW)
A lot of head vs. what typical 'non-welded oval-port 40 x 35.5' heads would be today straight from a CNC, dig?
Maybe that's why the 86b has worked as well as it has for me?
WRT RPM, I had a 5.5K chip in it for a while to break it in and shake it out.
Was fun enough down low that I forgot to take it out for a long time..
A 6K one went in, and way more fun, and had a lot more left for sure.
I banged it against the limiter again and again and it never showed any hint of float.
When it came apart it the guides and valve job were like brand new.
Never got around to going 6.5K, (or7) or taking it to the track or dyno or anything..
So maybe that's why i'm still so in love with it..?
So,
I'm really just like one of those guys like on TOS who say "gee it ran great",
without any real data/numbers..
FWIW..
