Hello, who does or knows someone that can do big highway miles with .800"+ lift and big spring pressures? What's the problems that will arise? Spring failure, lifters? Big cube mopar motor. Drag week style events etc.

Good question?
On my Victor MW heads, the short valve spring install height, and weak rocker shaft pedestals cast into the head were problem areas.
I ended up milling off the pedestals and using max wedge type rocker shaft blocks. T&D now offers paired shaft rockers that would be a better solution.
If going to custom rocker system, I would use valves with longer stems to make it easier to get more spring install height, then relocate the rockers for best geometry.
If looking for 0.800"+ lift I would use a 1.7:1 intake rocker arm, and for long life, a more gentle cam lobe profile that can be controlled with a lower rate valve spring.
An aggressive cam profile is going to want a high spring rate, which makes things harder on the valve train.
On my current setup, I believe my exhaust profile (Comp HXL) with 1.6:1 rockers is too aggressive. I have though of using a 1.5:1 ratio rocker arm, and a slower opening exhaust lobe profile to take strain off the valve train.
I like the idea of the bushed lifter bores with keyway roller lifters, but have no idea on how they would do with many miles on them? The keyed lifters should be lighter in weight (than the taller roller lifters with the cross bar) making the valve train more stable.
I'm running the PAC 1326 valve springs, but only 0.726" lift. It is 275 seat pressure and 663 spring rate. They list as 805 open pressure @ 0.800"

If you have room for a 1.625" diameter spring, something like the PAC-1328 installs at 2.100" with 280 pounds, and has a spring rate of 629, and at 0.900" lift the pressure is 847 pounds, if that will work with your cam selection?

You would want good oil cooling of the springs too.

I have been pushing street car boundaries for years with a big cam and cubes, except I am only at .750 lift in a 605 Hemi.....But even there, it has its price.

New Titanium lash caps every year cause they mushroom....Really have to keep an eye on the pushrod tips and oil spray...I used to burn up pushrods all the time. ...Hot springs is another issue...You have to have enough oil on the springs to not eat them up as well....A big pan and pump are really necessary when doing this.

I have eaten more valve train parts than most race shops over the years..A wedge would be way better than a Hemi for big cube street engine.Preferably a Predator head on Hemi block...

Good Vid
https://www.youtube.com/watch?v=PptxPDvbWsg

You'll wants lot of oil up there for freeway driving. I'm not sure what those guys do but something like adjustable spray bar oilers might be the trick. Turn up the volume for street driving, turn it down for high rpm drag racing.

I run a .805/.815 on the street in my 528" Hemi with Barton rocker system with spray bar oilers with no issues.

I thought my .690 was a lot on the street. Birdtracker

With??

From what I have seen is they put small ratio rockers on to make the street trips, like 1.2 ratio, & put the big ratio rockers on to race.

That's what I probably need to go to...Better check your lash caps though..

Well i might look into spray bar oiling. It's a 596" Predator engine but pretty mild with the .800 lift. I've heard about changing rocker ratio for race and street but i don't think there would be many options for these heads in ratio's.