Hey smart engine guys... can you help me?

I am getting very close to tracking down a beloved fastback formula s to buy. But I am facing the big block vers small block issue. So here's the question:
1. do any of you know the weight of the old stock 340's ... 67-69?
2. do any of you know the weight of the old stock 383's and 440's?
3. does anyone make an aluminum big block close to the weight of a 340?

now on an entirely different point....

my wonderful high school 340 formula s was a 4 speed and the plymouth mechanic who ordered it got it with the "optional" 4 speed cam. Do any of you know the specs (lift, duration, exhaust..etc) of the "optional" cam that could be ordered in 1968 for the 4 speed formula s?????

I appreciate any help you guys can offer ... this a body site is the best i've found on the internet..

jim coster, pittsburgh... (soon to be "fishing" again)