How fast can you go with a Magnum? Who has the quickest setup?

I don't know how capable the M-1 dual plane is. Yes, it is an aluminum version of the OE part, but what it takes to ring 450hp out of it and 360 cubes is a route that can vary a bit depending on the rest of the induction side.

You made a mention of it in the Duster with perhaps the OE fuel injection. I know of only 2 kits that will use fuel injection and the Hughes is one. A while back there was a similar set up with the MO single plane that was used. *I think* Mancini sold it. Someone with better grey matter material will have to find that for us right now.

Food for thought.....

Despite the constant ragging on the OE heads cracking (overrated concern) the OE head does power the create engine (360/380hp) to over 400hp via of the testimony of several dyno reports. FWIW, I normally have seen 415/420hp.

Would porting the heads add that extra 30/40hp? Probably so. I don't think you would have to go that far in porting ether. Someone that knows the MP head and the valve seat technical end with a bowl hogged out should be enough.
(IMO anyways)

The OE head maybe a $$$ cheaper option than the EQ head. Which is a very nice head.

What does the rest of the drivetrain consist of? Trans, rear & gears?