One additional point about the Kevko oil pan is that it doesn't hang much lower than the stock K-member. In fact, it might hang exactly as low as the stock k-member, but I haven't taken any measurements. I think this is a plus because I always worried about low hanging oil pans and the increased chance of pan damage if you hit something by accident in the street.
After building my 408, I read that using a stock oil pan could cost you as much as 40 HP because the crank would be spinning in the oil. The Kevko pan is suppose to offer the extra clearance neccessary to avoid this plus it holds an additional quart of oil. I think it was well worth the money.
