Nope, its not overkill. I went thru BG1 and TotSC for my guy. A lot of work went into him.
Elven Fighter/Thief.
Str 19 (18 +1 for the tome)
Dex 20 (19 for the elf +1 for the tome or it may still be 19, i dont recall)
Con 18 (17 elf penalty +1 for the tome)
Int 12
Wis 15
Cha 15 or 16. i dont recall.
The game is still a challenge. if you think about it the Dex of 19 is not uncommon for an Elf and there are many girdles available to increase your Str to 19 and beyond within the game, add Int and Wis potions that are freely available too and it's fairly easy for anyone to (temporarily for a given battle) surpass your stat's without unbalancing things. You rolled him, you can legally use the tomes and legally import him into bg2, enjoy.
PS. Good roll btw.
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It's bleedin dark down here, slippery too.

Man, that's a pisser.