Necrognomicon has excellent lists for classic necromancer skill caps (which are valid for any int-caster):
http://www.necrognomicon.com/skills1.html
http://www.necrognomicon.com/skills2.html
http://www.necrognomicon.com/skills3.html
http://www.necrognomicon.com/skills4.html
However, some skill caps are not really "classic" on this server.
For example: Sense Heading should cap at 5 x (level + 1) in classic, though currently there is no such cap on p99.
Tradeskills should all cap at 200 (tradeskill specialization came only shortly before Velious), though there seems to be no such tradeskill cap on p99.