hobot ain't no cam shaft authority but do know flat is flat and angled is angled and mixing the two is bad juju for faster wear. Comstock is best to judge this, but likely can run it w/o issue for a good while but at some point expect to need lifters resurfaced when renewing the cam. Comstock and others reviewing cam wear and hardness have concluded the main wear factor is quality of oil.
Can you show us the bottoms of the lifters? That may be best indicator to use or re-new. There is a lot going for welded up then re-ground cams off a good core.