67FEfastback, The weight different is the issue of aluminum over iron just like the heads and intake manifold. All aluminum motor is 496 pounds if a Shelby. That is with a cast 428 crank shaft. Full iron block is 640 but question that number too.
You are hooked on the racing bug. The motor has to be built for this kind of event. The problem with FE blocks poor
oil returns, running street
oil pressure of 60 psi on the track and low
oil pressure when running too when hot. On the track need a min of 75-80 psi PERIOD. You want to run 60 psi, go ahead. After a couple of "G" turns and the oil being slow to return to the pan, you will have low pressure to the back of the motor and running #4 and #5 mains low as well as cylinders 3,4,7,and 8 rod bearings. The reading on the oil gauage IS NOT what the back of the motor is seeing. There is a 15-30 psi drop from front to back of motor. The SO motor is better with direct oiling going to the mains first instead of the center of the block. Limiters in the heads of no less than #.080 if running shaft rockers or you could have a blueing problem with adjusters and push rod ends also. May sure that you smooth out the openings in the intake manifold to help oil return to oil pan.
Accusump, been running one for 10 years. Having a 3 quart safety net when racing and has saved my motor 2 times from rocker shaft breakage. There is always a place to put the tank. Hook up a quick connect when racing and remove it when street driving. They are electrical to control, even mount it in the trunk.
Aluminum has many pluses over iron. Weight alone, Most cars and trucks are running aluminum blocks that last 150,000 miles with basic maintainance. These new blocks are fine. Dry sump system is the way to go if you are going to stay on the track. If you are staying wetsump we need to improve the oiling system, control of flow, returns to pan, and maybe an added supply lines to the back of the block. Rick L.