hello grumpy I have one of those unmentionable 383 crate engines broke a couple parts at 300 klms from new fixed that problem myself as it was cheaper to do than pay transport costs got it through to 1,000 klms no dramas so I put it on the dyno and surprise , surprise the 383 produced a massive 262 rwhp (ha ha) I think that a motor this size should produce more what do you think I am attaching a parts list for you and relavent dyno sheet for informational purposes only thanks 750 vac cust headers single 3 inch exhaust