I would agree with changing the water pump when doing it, and I would also agree with sticking to the AC Delco for the opti spark. I use the MSD for the coil, but not for the opti. I know lots of people have good luck with the MSD, but I have seen them bad out of the box too. I don't see nearly as many issues with the Ac Delco.
'95 Z28 with full length tuned headers, catalytic converter delete, full hooker Super comp exhaust, performance cam with 1.6 ratio roller rockers, ported and polished heads and matching intake, egr delete, air pump delete, ford green top racing 42# injectors, and fully tuned!