I know a factory Iron small block head weighs about 1 pound more than an iron big block 906

I figure aluminum from iron saves 20 pounds per head...a smallblock is more like 22.

BB Water pump housing saves 10 pounds, pump maybe 2. SB's already aluminum!

Intake I think I figure 35 iron 383 vs between 15 and 18 pound for aluminum.

aluminum radiator maybe 10-12

Lighter bobweight rotating assembly can easily save 6-8 pounds

B motor pushrods weigh ~1 oz less than RB....that's a pound right there!

Headers, too many variables, thick flange headers with 16 gauge tubes might be a wash compared to cast iron....cheapie 18 gauge with 1/4" flanges probably save 10 pounds each. Too many variables.

so I figure my installed aluminum low deck 517 with the radiator saves about 90 pounds over the the original 440 that the car came with.....or about the same as a factory 340 would weigh. it'd be a little lighter without the hard block but I'd rather have it in there

I don't think a bare 440 long block with an intake is really 120 pounds heavier than a 340, the block is roughly 60 pounds more but the heads and intake are probalby 10 pounds less (340 4bbls Iron is a comparatively heavy piece) but even adding the crank difference it's hard to find an answer that adds up to the other 60. But maybe it is over 100 with the manifolds.

Also Static weight probably isn't as big a factor as dynamic weight....stepping the aluminum heads not only lowers the mass and decreases the front weight bias...it also lowers the center of gravity. Dynamically taking off 10 pounds with an aluminum radiator hanging 2 feet ahead of the axle is like taking off 20 1 foot ahead

Your answers may vary but you really need to scale it if you want to know for sure. you can get carried a way...Ex: A holley is a few pouunds heavier than an aluminum carter