I wouldnt add that much weight to a cowl. Too hard to make something that will hold together long term. I would use a cf pushrod for the elevator. There is at least 1/2 lb of nose weight gone. Then I would build a shelf on the firewall above the engine to get the weight as far forward as possible. Use your lead sheet here and stack/ form it to fit within the cowl but not be attached to it. I like to build boxes to contain my lead shot or powder, when i have the right amount i will put it in a paper cup, dump in some gorilla glue, add a splash of water and mix till all the lead shot is coated. Then i dump it back in the box and let it set up. You dont need a lot of glue and it will foam up and lock it all together. You can also dig it out vice using epoxy.