looking for option strategy

I have found a few stocks that have have wildly different Implied Volatilities for Puts and Calls.

Calls are around 25%
Puts are around 40%

For those interested the stock is QANTAS.

Obviously the market makers have a downward bias on share price movement.

To take advantage of this volatility bias I was looking at combination spreads.

Probably some sort of Calender spread such that short term write Puts, long term buy calls.

This is implicitly a bullish strategy, and I was looking more at a neutral strategy on these stocks.