Building a frame from scratch is a large project, having something to copy or good plans is a must.
I would follow ScratchBuilders advise and contact Chuck.
I have built a few 427 type frames now, believe me, it is a lot of work but also very satisfying if you can pull it off.
One of my build links,
New Build
Here is a pic of one of my 427 frames I just completed and dropped off to powder coating last week.
IMO, It will make your task a lot easier if you have all your suspension and body first.
I say have a go and good luck!