[dsraven]

for those parts it likely isn't gonna matter too much where your parts come from as they aren't really outside body parts. i would recommend, however, that you take some good measurements and take pics of them as you measure. that way you can get the dimensions correct when you weld in the new parts. the cowl isn't that important but the hinge pillar stuff can be because the door has to fit and seal afterwards.
when i do that stuff i cut a few patterns from poster board that shows the contours and where the bolt holes go etc. take a reference from something like the upper hinge bolt holes or whatever when you do the hinge pillar work. I also use a center punch mark above the work area as a refernce for my pattern to use as a common starting point.