Sticky #3
I read carefully what you wrote above, including your "fixed specification". However, for the record, if I were seeking to build a 550 BHP 351C with individual runner carburetion using off-the-shelf parts, I'd use Trick Flow CNC 2V heads, the Aussie Speed Weber manifold, and the popular Weber 48 IDF carbs. That is a 550+ bhp combination. I don't understand choosing to use a carb with the "owner dissatisfaction" record of the 48 IDA.
Did you hear the sound of all those toes cracking when I just stepped on them?
550 horsepower will be easy to achieve with IR carburetion & bundle of snakes exhaust, regardless of which heads you choose. It can be done with a power band that pulls well from 1000 to 7000 rpm, including having low rpm power and drivability. Individual runner carburetion actually improves the low rpm performance of engines with "big cams" if the carbs are set-up and calibrated properly.
Revving to 7000 rpm isn't difficult, but you'll need to decide what type of valve train your engine shall employ before you can discuss a strategy for making it capable of revving that high. Windage trays are a non-issue, whatever racing oil pan you choose shall have a built-in windage tray. The 3 pans mentioned in sticky #3 are all good. I applaud your choice of a 3.5" stroke crankshaft. The stock crank is fully up to the chore of occasional blasts to 7000 rpm. Its been used for 10,000 rpm Pro-Stock drag racing, and 8500 rpm NASCAR racing (500 mile Sunday afternoon drives). If you must have an aftermarket crank select a sportsman crank from a major racing crank supplier like Calles or Bryant, one that the manufacturer specifically claims has been designed to minimize bearing load. The best cranks are fully counterweighted, they are expensive, they are overkill for your application, but they reduce stress on the block and make more horsepower (less power losses compared to a partially counter weighted crank). There are three Weber IDA manifolds available (1) The first is the original manifold designed for 4V heads sold by De Tomaso. Hall Pantera duplicated that manifold, and the Hall Pantera version is the one commonly used. The original De Tomaso version is strictly an expensive collectors item today. (2) The second manifold was also produced and sold by Hall Pantera. It is based on the 4V manifold, but modified to mate with the first generation SVO racing heads. (3) The third manifold is produced and sold by Red Line of Australia. It is designed for 2V heads, but the flanges around the runners that mate with the cylinder heads are large enough to seal up against the larger 4V intake ports. That manifold is not common or popular here in the North America. So in terms of head & manifold compatibility, you can select iron 4V heads, you can select CHI 4V heads, you can fill the bottom of the 4V manifold runners with epoxy and select stuffed port heads from CHI or SCM (CHI calls them 3V heads). You can also select 1980s vintage SVO "A3" race heads or 2V heads (iron 2V heads, Trick Flow 2V heads, etc). I'd select the heads with the best Westlake/Yates high swirl combustion chamber and let a "porter" optimize air flow in whatever heads you choose. People too often overlook the importance of "thermal efficiency" and place all their attention on "volumetric efficiency" (air flow). Heads with Cleveland port geometry and 4V port height can all be ported (by the right person) to flow in the ballpark of each other, that includes the factory iron castings. In my estimation the SCM heads are the best heads out of the box among the heads with 4V height intake ports. They are CNC ported, they have a good exhaust port, the ports are non-turbulent, they have 2.19" intake valves, and they have the best high swirl combustion chamber design. SCM heads are also available with "dropped" combustion chambers. Dropping the combustion chamber achieves the same thing as raising the intake port, but it does so without moving the port entrance. Dished pistons are used to compensate for the decrease in combustion chamber volume. The dropped chamber heads are capable of flowing around 400 cfm. And at that point they are walking away from any other head I've mentioned.
Edit: The thought occurred to me, the runners of the Hall Pantera Weber manifold designed for the SVO A3 cylinder heads may match the intake ports of the SCM cylinder heads. That might be something to investigate.
Good luck with your project.