Riley, I'm not going to comment on your cam choices but I'll offer a few comments on your problem. A recent article written by a reputable engine shop says that with a flat tappet cam it's not a question of IF it will fail, it's only a question of WHEN it will fail. While zinc/phosphorus (ZDDP) are critical to high point load surfaces, the level of ZDDP is even more critical. It's a common mistake that "If a little is good, more is better" when it comes to oils and additives. Too much ZDDP causes zinc and/or phosphorus to precipitate out under high pressure loads, and actually deposit on the cam/lifter/bearing surfaces and then sluff off, leaving microscopic fissures behind.
For me the answer is simply don't run flat tappets if a conversion to roller lifters is an option. In the event that there's no choice but to run flat tappets then for me the only answer is to 1) run a top quality break in oil that has the proper formulation of ZDDP; 2) follow the break in instructions religiously; 3) drain the break in oil according to instructions, and replace with a top quality racing oil that contains the proper formulation of ZDDP; and 4) never run any type of additive that messes up the chemistry of the oil. The oil of choice for me would be Brad Penn's Racing Oil. Just my $0.02, and I'll step down from the soap box.