You are comparing big block FE with tall deck small blocks, apples and oranges, at that the Cleveland small blocks are heavier than the so called Windsor small blocks , either standerd or tall deck 351 based.
The FE/FT (Ford Truck, steel crank) ran from 330 inches up to 428, identical block dimesions.
390 has a 4.05 bore and a 3.78 stroke, where as the 428 has a 4.13 bore and a 3.98 stroke. The externals on the blocks are identical and the stock 428s used 390 heads and cams.
All FE and FT engines have a bore spacing (distance between cylinder centers) of 4.630 in (117.6 mm), and a deck height (distance from crank center to top of block) of 10.170 in (258.3 mm). The main journal (crankshaft bearing) diameter is 2.749 in (69.8 mm). Within the family of Ford engines of the time, the FE was neither the largest nor smallest block.
The FE block was manufactured using a thinwall casting technique, where Ford engineers determined the required amount of metal and re-engineered the casting process to allow for consistent dimensional results. A Ford FE from the factory weighed 650 lb (295 kg) with all iron components, while similar seven-liter offerings from GM and Chrysler weighed over 700 lb (318 kg). With an aluminum intake and aluminum water pump the FE could be reduced to under 600 lb (272 kg). This weight saving was significant to boaters and racers.
The FE,,, are all iron, and bloody heavy. A lot heavier than a small block Chev, or small block Fords. Or the 429/460
Yes they maybe a similar weight to a BB Chev or Mopar both are better engines and have more capacity.
A 400 Chev is far smaller than a 390 FE. I would probably prefer the 390 FE,, in a full size car. But Ford also made a 400ci Cleveland based tall deck engine which was far more modern. The engine that mine and most Aussie assembled ones has.
The Mopar and Chev have a far bigger range of alloy aftermarket parts than the FE. And did in even the late 60s, and head by the mid 70s.
In 69 Chevrolet had an aluminium engine available!
As an aside to all of this I own a 71 Galaxie that in the US had a huge range of engines. 240ci 6, 302W V8, 351W V8, 400M engine V8 and 429 both base models and Super cobrajets as well as the venerable 390 in base and 4 barrell form. This in a 2 tonne full size family car.
It was Fords out with the old and in with the new engine year.