FRPP just released the Sportsman 302 block, still lots cheaper than an R302 but not cheap by any means. Back to the topic, factory rates stock 302 blocks to 450 hp, not 550. Anything over 500 is PUSHING it bigtime, no matter what power adder. 2 bolt mains and relatively small main webbing aren't good for longetivity. If you keep the RPM's down and drive reasonably I could foresee it lasting quite a while, but it'd be on the edge.
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1991 LX Hatch 5.0L