mattpatt There are a couple of things left out besides weight.
#1 if you are going to build a motor, what are the heads made out of?? iron or Aluminum? Same for the intake. Cross matching runs into trouble over time. This is an iron and aluminum part. The expansion rates are not the same and cause leaks of coolant or
oil. Either inside or out of the motor. IMO Stay with one metal.
#2 If you damage a block, window or spin a bearing. IMO alot easier to repair and reuse unless it's cracked down the main gallery of the block. Ford has had some problem withthis on the small blocks. These blocks are also thin wall motors like the 427. Aftermarket blocks have alot of room for stroker kits. 351 blocks are running 460 cubes and still getting bigger. Same for FE motors going to 527 and now almost 600 cubes.
#3 There are only a couple of Racers and builders making new parts for the FE motor which give the advantage to the 351 motor for better parts and cheaper. Nascar motors can be gotten used and need some work for street usage.
#4 Wieght wise my all aluminum shelby is 492 pounds with iron crank and steel rods. This is iron small block wieght with about 100-150 ft of extra torque. This is the last and main thing, build a motor with the broadest power band you can. For get about the HP numbers. Build TORQUE, this is what moves the car. Keep the rpm max around 6,000 rpms for and FE and 6,500 for a windsor and you will have many years for fun with low maintainance. Go for more power, higher rpms, and the life of the motor drops. Also have you ever driven a 2,500 pound car with a 500/500 hp torque car??
They are a handful.
Rick L.