Whose Hydraulic Flat Tappet Lifters?

In Nov. 2014 I installed a Compcams 20-221 cam and lifters in my magnum-headed LA 318 daily driver. During the break-in the mechanical fuel pump went bad. That was about 3 mins into it. I couldn't keep the engine rpms up. I finally shut her down, bought and installed a new fuel pump then restarted the engine and completed the break-in. I still have the low oil pressure at hot idle but have not heard any noise from those lifters.