if i could start over and had to opt for that year, i, personally, would get a '98 12 valve.
to answer your question.
if you stay stock... ... the only issue you'd find yourself worrying about are lift and injection pump failure which could be pretty much avoided with an upgraded lift pump (which would "save" your injection pump) of which there are many ways to go from $100 to $400. you may wish to do some minor transmission mods even on a truck that's going to stay stockish.
if you build a power beast you will be buying upgrades/repairs indefinately.
also, there are some block cracking issues with some of this truck. do a search for "53 block".
what kind of shape its in now and what you plan to do with it in the future are going to matter most. if you keep loads hauled within the designed limits, which many do not, this truck may last a really long time.
there are many folks who leave their trucks stock and take good care of them and have no issues.
i've not suffered any of the "common" issues people discuss about this truck but i fret about them. i've considered selling it based solely on paranoia.
i do wish i kept the engine stock and only upgraded the transmission, brakes and suspension.
one thing is for sure, all considered, this 98. 5 should be a big improvement over that '82 gmc.
you know a used truck is a gamble... . *****, a NEW truck is a gamble!!
good luck, jeff