I don't like a 5.3L but thats me. If your going to do an LS swap, then put a 6.0L or a 6.2L. The 5.7L is the most versatile engine GM ever built. The last GM 5.7L (350s) are very dependable. If you are doing BMWs, there is no reason you cant do a 5.7L They are a simple design, that was first introduced in the 1950s.