I'm looking to do a new build for a lightweight Fox. I'm aiming for 400rwhp. I've searched and their are many threads supporting one or the other. The block will be a factory piece so I'm looking for the safest build. Do I stress the block with a hot 347 or turbo a HCI 302? Streetability seems to suffer with a 400rwhp 347. I would think a turbo car with stockish cam would be easier on the block. Here's the kicker. I'm limited to 91 octane pump gas and the engine will be tested by the 110* plus days in Phoenix. I realize a Dart block will cure any worries but I'm looking to both keep the car light and I already have a stock machined block. I'm leaning towards an old school build for the heck of it. Ideas?