Zorro cannot plan to implement a better margin calculation, but you should plan this, or your backtest can be off by a large factor when you trade option combos.

Get the margin formula of your combo from your broker and put it in the script. For example, if the margin for a vertical spread is the strike difference, set

MarginCost = 0.5 * abs(Strike1-Strike2);

before entering the two trades. This is important for a realistic backtest since margin directly affects the annual return.