It's tough to make a mental transition from your typical 3600 pound street machine and a 2400 pound Cobra until you're actually driving one. You don't need to go overboard on a 600 HP monster engine to have all the power you need on a mostly street driven Cobra. Gross excesses are not required, or even desirable. Build your engine slightly on the conservative side. You, and it will have a happier relationship in daily living with each other. Build it hot, and you build it tempermental. Not a happy situation.
Check the SVO Catalog, and you'll find the weight savings for an aluminum block (120#), and an iron block (195#) is simply not worth the extra cost in $$$, and reliability for street and ocassional track use. Use a well seasoned production block, and spend your money on good bottom end ARP hardware holding it together.
Gears vs chain on the street. Remember when (and likely still today) when the cam gear was sintered iron or cast aluminum, and the gear itself was nylon, or plastic. For a mostly street and ocassionally track use, the double roller chain from Cloyce or any of the cam vendors will more than suffice. The gears will last forever, and the chain will get replaced with rings and valvegrinds.
Retrofit hydraulic roller cams (and roller rocker arms) are a definate "Go for it" if you have the budget. Well worth the extra $$$! Makes your engine think it has grown an extra 50 ci. Tip. Have your valve springs
oil retentitive coated for cooling. They'll last longer before needing replacement. Keep the duration where you realistically expect to use the motors' power band. 220 - 225 I, 220 - 235E regardless of lift. Good street manners, and awsome torque when the tach hits 3000.
Most will disagree with me on this point. Don't use aluminum roller rocker arms on a street engine. Use steel. Specifically, Comp Cams Pro Magnum steel roller rockers. They last forever. (Actually, they don't last forever. Comp Cams recommends you send them back for a rebuild when the engine is down for rings and/or valvegrind). Aluminum rockers are a throw-away item for replacement every racing season.
The nemisis of the Ford Windsor engine, 289, 302, 351 has always been in the breathing department. Chuck the stockers in the dumpster. There is nothing you can do to help them. Aftermarket is the way to go. Roush, TFS, Edelbrock, AR, and others make vastly superior heads for the 351W motor. 2.02/1.60 is the minimum valve size for a 351 size motor. 393 stroker, look to upping that to 2.08/1.60. (The Aussies, where the 351C is well supported, have a C3V aluminum head for this motor. 2V ports, 4V valve sizes) (Some BBC folks have this combination on their street 454's via Dart - awsome mid range torque).
What I have come to hate about Fords! The starter, the distributor, the alternator, and the power steering pump. With a Cobra, you have a choice. Summit sells a Powermaster starter, new, that's 1/3 the size and weight, and lasts forever. $160. Distributor. The MSD is a Delco distributor on a Ford stalk. Get one. Likewise for a Delco alternator. Change the brushes every 100,000 miles, and bolt it back in. Likewise for the Saginaw PS pump. Keep it full, and filtered, and it will outlast the car.
OK. I'm off my soapbox. Mr. Fixit, anything to add?