If it's all about weight you can experiment other ways to figure out how much it will actually help... I'd relocated the battery and put on stickier tires first and see how it improves. You'd also lose roughly the same weight for a lot less cost and hassle by swapping that steel hood for a fiberglass one. Personally I wouldn't go through the trouble of swapping to aluminum heads if I already have good-flowing iron ones unless they're the "next level" in power potential, like the Eddy Victors or other big-port competition AL heads.
