If you don't have a furler, there is no reason for an inner stay on your boat. I agree with Faster. Convert your sails to hank on - or get a furler and install a Solent stay.
To sail your boat as a Cutter: 1. the mast is too far forward. 2. the sails you have are not cut properly to sail as a cutter rig - the outer sail should be high cut and the inner sail should be lower cut. 3. You will gain no speed as a sloop rig is more efficient.
Living aboard in Victoria Harbour