It's worth the build. You can use most of the parts in your sig except the lower intake, u can use the upper with a lightning lower. You will need to either get a roller block or convert an older block to roller which can get expensive.
You can use these parts to get it in the car and running but you will need better heads and a bigger cam designed for a 351 to make a real performer. Not to mention that there are a few swap parts that will be needed. Do the build, you will never look back.