I have an 87 Suburban block that was set up for roller cam or so I thought. Lifter bores were counter bored that releived oil pressure. I have a 99 vortex fuel injection system with plastic front cover & crank sensor. I have gone to a flat tappet cam but have no way of securing cam with plastic front cover. Is there a flat tappet cam that is set up with a retainer groove. Thanks Zeker8