With the Truvativ conversion, you should be good to go. Your current BB has the bearings in it.

This looks like a really fun project! Great job so far, and kudos to you for jumping right in! What a great way to get comfortable with wrenching on bikes.

Based on the components that you have obtained for your build, it would appear that you might be seeking a "sporty" riding style. Just know that the frame you're working with is not a very "sporty" frame (its quality is quite low and its geometry is pretty laid back), so if you desire something sportier, All you have to do is swap everything over to another frame whenever it is time to do so. A track frame or road racing frame (with horizontal dropouts) would do the trick.

In the mean time, enjoy the process, and please post pics of your build! It should be a very cool bike.