I've gone down this road and priced it all out. Not worth it.
A) The Boss rods and pistons are marginally better. Roughly 10% more power could be obtained, safely.
B) You still bring into play needing to replace other parts...ARP hardware, billet oil pump gears, Boss valve springs, Boss tensioners, head gaskets, Boss crank, etc.
C) If your block is damaged, machining will need to be done.
IMO, it's not worth it. For a little more more money, you can have a fully forged rotating assembly that will support much more power. The last thing you want to do, is spend all that money to buy the Boss parts for it to be replaced again. Spend the money once and get a quality motor. I don't trust many of the shops around here to build a motor, so my purchase will be a factory Ford assembled motor or Livernois.
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