408W or 427W

[blykins]

Like I said, it's your choice on what the budget will allow. I was just trying to give you some food for thought as I do these kinds of combinations all the time and I'm familiar with what machining needs to be done, what kind of power is expected, etc.

The difference in price that I was talking about was not only the additional cost of the block, but the fact that you have to use an SVO style crankshaft, which in turn requires H series bearings. With only a 500hp requirement, a production block and a Scat cast crankshaft will suffice with tons of room to spare. Also, keep in mind that a Dart block doesn't come fully machined. They need square decked to fit your rotating assembly, cylinders finish honed to fit the pistons, and the mains checked. I treat them like I do any other block when it comes to the machine work.

If you have an RPM Airgap, you're not necessarily working with an intake that won't flow. These can be made to flow very well and if your focus is on torque with some great mid range power, then I don't see anything against using it.

The pricing for any cubic inch displacement is pretty much the same when dealing with the forged rotating assemblies. So if a 445 or 460 is the same price as a 427, then in my opinion, it's better to get more for your money. You can always upgrade intake manifolds later. Your sidepipes are going to be a bottleneck no matter what displacement you go with, but a header that will support a 393W will not support a 427W that makes considerably more horsepower.