Twin Keel vs Bulb Keel
Stainless steel may actually be a worse choice because it is even more prone to crevice corrosion and because it is dimensionally pretty unstable when heated. When you apply heat to stainless steel to stainless it tends to distort and lose fairness. It is also quite difficult to get bottom paint and fairing materials to adhere to stainless steel but stainless steel provides a poor surface for fouling meaning that barnacles can adhere to the stainless steel very tenaciously.
This is sounding like a worse idea with each post. Why not pour the keel and attach it as it has successfully been done for the past two or so centuries. It will be cheaper and easier and have a better result in the long run.