Supposedly the old MP formulas for figuring horsepower by (1) trap speed (MPH) (2) weight and (3) maybe a third one: were simple but were proven to be very accurate. As said I'd fix the dead hole and yes street dominator intakes are very low profile

The 8008/8009 is the next step. The 440 Weiand Action + sacrifices nothing, and might gain some mid range.

Unless, you try to "carb pad mill" the performer . Easy to shave off .25" of raised material from body.

The Action plus can be pad milled to less height than OEM.

Surprised that no one here mentioned this, or maybe they did and i missed it... but keep in mind your 280HP (which we've now guesstimated to be over 300HP with all 8 firing) cannot be compared to the 500HP number you see posted so often here. RWHP vs crank HP. That 500HP 440 build will not be anywhere near that on the same chassis dyno you just used. A 500RWHP Mopar would be one mean-ass big block.

I would have suggested possibly modifying a Street Dominator intake (trimming the pad) and possibly even modifying the air cleaner if possible, but i doubt that would work for one reason, in MY experience, that intake barely even works without a spacer on top. Mine is 1" and i'm willing to bet it wants more. Maybe my combo is goofy, but that spacer is mandatory. So obviously that wouldn't work at all for you.

Someone here said that the Performer (or similar) intake is no improvement, i disagree. The weight is the improvement. Mopars are too heavy, a bunch off the front end is always a good thing.

Also, whoever told you to get 906's shouldn't be telling anyone what to do. Its pretty much the same head you have, just more expensive to buy used. If you're going to rebuild the engine (read: buy new MODERN pistons) then maybe get some ported 915's or aftermarket aluminum, if not, either port yours or leave it alone.

I personally like the Holley DP design more than the Edelbrock/Carter carb, but i've used both and the latter is fine. That engine probably wants a bigger carb though. Mine wanted more than an open, stub-stacked 750 Holley, and it was considerably less modified than yours. Mine also liked 94 octane. It was a low-compression 440 too, go figure. These engines are not efficient in design...

I'm with Sheldon though, sounds like with a really good tune, recurved distributor and just some good attention to detail in the powertrain from front to back this thing will keep you happy. Though i'd recommend a mandrel bent, aftermarket 3" exhaust system... that'll put a big stupid grin on your face that wont leave for a week...

Heh... and for all the posters suggesting you take it to the track, you might wanna remind them that in this idiot province (i live here too), Nanaimo might as well be 500 miles from Mission Raceways, with those insane ferry prices. It might be a bit cheaper to the Sunshine Coast, but then thats only an 1/8th mile track...