New cam working fine.

[b5blue]

  Installed a new flat tappet cam using exact guidelines from Hughes Engines. Got about 80 miles on it and no issues.
https://www.hughesengines.com

[Kern Dog]

Way to go, man.   
I don't recall which engine you have. How big is the cam? It looks like the cam and lifter failures are more likely with the cams that require much stiffer springs. I have 5 old fashioned flat tappet engines in cars out back and the only one that has eaten cams is the one with the most cubes and biggest cam.
I've asked around on the forums and raked in some good advice regarding cam and lifter longevity.
Dwayne Porter is a guy in Vermont that has chimed in several times to say that you can do everything right and still munch a cam but....he deals almost exclusively in higher performance stuff. It isn't the cam itself that is the main fault, it is the lifters and the taper on the bottom of them. There are a few machinists that rebuild and regrind USED lifters to the proper taper. Dwayne was the one that blamed the oil I was using on my cam failure in 2022. I switched to a synthetic that claimed to have added ZDDP but being an emission compliant blend, it also had HIGH detergent. The detergent acted like a squeegee, wiping off the zinc as fast as it splashed it on, making it worthless.
I don't mean to be a wet blanket here. I'm willing to let bygones be just that as long as you play nice too. I do hope that this works out for you. If you get a chance, take a video, post it to YouTube and post it here to share.
Good luck, man!

[375instroke]

I put a new flat tappet cam in two years ago, 15,000 miles on it, and it suddenly went flat, with another lifter just starting to go.

[Kern Dog]

See, there is the down side.... 

The flat tappet design seems ripe for destruction if you don't know how they work. It is a constant metal on metal sliding action that relies on a thin film of oil for lubrication. Stiff springs, improper taper on the cam OR the lifters, inadequate oil...all sorts of things can go wrong.
It sure seems like the best chance for survival is by using a mild camshaft and soft springs but that means low performance.