Well, you aren't the first person to initiate such a project and you won't be the last. My first question to you would be "what is original engine in your car?" I would guess a 318?
I only ask this because most of us here would not consider replacing a factory 340 with anything else - or at least not a big-block conversion. Many of us here would offer an alternative - ie: stroker kit for 360 - one version gets you to 408 - and that would leave you with a much lighter weight in front end.
I am sure someone will endorse the 440 idea and provide lots of advice and tips. good luck