Lighter yes but not by much especially after you start adding aluminum parts..... You can put an overdrive on a big block...dollar for dollar, it seems like big blocks have better support in the after market, parts seem on par or cheaper..... More torque, 440 and strokers are larger and there for will make more torque than a 408 a rebuilt 400 is same size and a rebuilt 383 comes to 389-396 not much smaller and a lot cheaper....smoking big blocks,
I don't know your combo but if you got a well setup 500 plus hp 408, there ain't that many 500 hp cars running around big block or not, I could build a 700 hp 273 and say other engine are lesser than 273's cause they can't touch it. But don't make 273 better in general.... Anything you can do to 340/360 you can do to 400/440 and gonna make more power dollar for dollar.... I can see the appeal of the 408, and may build one, one day for my 65 Cuda since big blocks don't fit to well in early A bodies, but to me if a 340/360 don't fit your needs, time to go big block.
