650g isn't an issue on the whole. Pretty much any of the packs will be fine. The one you picked GNR Racer should be good for 15+ minutes of track race time. The 5000 would be closer to 20.
1800KV is perhaps a little quick for 5S, but it depends on the track - it shouldn't be any kind of problem - just tune using gearing. If I were to run 5S in my truggy (planning to do so), I'd be going with the Tekin 1550KV, but then I have a relaxed, slow on and off the throttle driving style - very smooth, but not really fast.
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