You dont mention the year of the 454 so this is a generic response.
Cam wear pics you posted point to excessive valve seat pressures....maximum seat pressure in a race engine running a flat cam is around 135 lbs....
I always keep street flat am seat pressures around 100 max...ask the shop if they even measured the seat pressures...did they provide you with a build spec card?
Anything higher and the followers end up galled up destroying cam lobes...plus push rod ends gall out just like your pic.
Your pic of the cam lobe showing a widened run mark tells me the cam is also floating back and forth in the engine....making me wonder if the cam was installed correctly...I have seen later cam gear sets installed on early engines and the cam walks back and forth an 1/8"...
Finally...valves sticking....if the heads have had the valve guides knurled the guides may now be too tight on the valve stems..a valve can also "stick" if the valve head has contacted a piston and bent the stem....you list a .501 lift figure...that combined with a 1.75 ratio roller gives you 0.089 lift into that chamber...depending on where your cam is set and the lobe centers....flat top pistons would be running very close to those valves....deck clearance and head gasket thickness come into play....but this seems a little risky to me...
As mentioned previously...flat tappet cam engines MUST be run in on an oil specially designed for flat cam engine run in...products like Lucas 10627 oil or Royal Purple Break in Oil contain high zinc components to protect the rubbing surfaces during break in. Some modern oils have some zinc, but nowhere hear enough to do the job correctly.
As always...the above is just my opinion...
