i had an electric water pump on my firebird, i loved it simply because my car never went above 180 degrees..
it might be good for 2-3 hp but not 8-10. i dont know how the water pumps work on ls1s but my lt1 water pump was cam driven, of course the more free-moving the cam is, the less parasitic loss in power you will experience, same with belt driven pumps like on sbc's but the gains are tiny.