I've lost count of how many blown up roller cam motors I've bought in the last 35 years. Can't remember buying any blown up flat tappet motors. The lift you are asking for doesn't take much spring pressure over stock. It should last forever. Flat tappet motors also make their power at a lower rpm, which makes for a longer life engine. Nearly all drag racers think they have to have a roller cam. What a joke. You can make over 800 HP with a low rpm, low spring pressure flat tappet that will last a long time.