I mean i get it....... but a task like this is for someone who has all the skills or its going to be fkn expensive or have a lot of road blocks. Not sure this is a project you want to be learning to weld on. I would make the parts but get a fabricator to do the welds. I tacked all my k frame stifeners in and then had my fabricator weld it all. Same as the chassis stifeners. I had to scribe them for hours to fit then tacked them and he came in and welded them, that way i know the welds are perfect and as strong as can be also welding thick gauge steel to the thin floor pan isnt easy if you have any rust pits it will juts blow holes.
The weight isnt great however no different to have few heavy blokes in the car.
Brakes wilwoods will be fine but there is better out there, also do a decent rear disk as well. Runa good width tyre probably not the car to run a front runner on lol.
I am sure you realise that this is a huge task and you not even scratched the surface of it. Going to be a long build, staying motivated will be the hard bit