With ALLOW_OLD_POWER_SYSTEM = true //ALLOW_OLD_POWER_SYSTEM as server option, old power ships still act like new power ships that have no reactor on it.
What it looks like for an isanth.
GUI reports it correctly, the ship acts as if I'm flying a ship core with a lot of extra mass. Can shoot my weapons only once on spawn (initial charge) and defensive effects cannot be toggled.