The rule of thumb for motor is always 280kv or lower with 1:3 gear ratio at minimum. This is by far the safest point to get started. If you buy cheap motor with higher kv, the chances if its not strong enough is that you will need to buy another one in which it will cost you more money.
6 cells lipo ok.
60 AMP esc abit low, get something more than 100 AMP so that it doesn't get easily over heating.
Low specs for electric longboard works, but it wil get burned down / broken very fast.
These motors and electronics are meant to run 3kg object and not 60kg++
So keep in mind, more torque + better electronics = longer life + pleasure experience.