[Skuzzy]

Working from some level of long term memory, I recall an all iron 351W weighing about 140 pounds less than an all iron FE.

Replace the iron components, in both, with aluminum (block, heads, intake, water pump) and the gap closes a bit. Around 110 pounds difference, if I recall. It will vary some based on which aluminum components used.

All the main engine parts are smaller on a modern Windsor. Crank mains are the same size, rods are shorter, rod throws are smaller, crankshaft is shorter, block is smaller, heads are shorter, and so on.