I had a pair of 98's.
one broke a lifter around 190 hrs, due
to the valve spring issue they had with
that era of engines, after that, ran them
another 250 hrs without any issue.
They run on 87 octane
Some say do the springs/lifters around 200 hrs.
Reliable ?....I'd say there as reliable as reg 502/415
I would have no problem owning them again.