I have replaced the inner fender panel from the shock tower to firewall where the battery exploded on my 280ZXT, and half of the firewall.
I am glad that I bought a bead roller, because I was able to fabricate panels with the stiffening beads in them.
I borrowed a friends' sheet metal brake to bend a 90 degree flange, then 'slotted' the leg of the flange that had to be contoured for the inner fender [anel to 'roll' down fo the frame rail from the top of the fender.
A lot of vise work and bending to get the right contours, but well worth the effort.
I actually used 4 pieces - easier to work with several small pieces than 1 or 2 bigger - especially w/the bead roller.
I was lucky to have been able to cut a battery tray out of a donor car that my friend had - but I did have to fabricate the lower side support for it - matchibg the contours that were already there "think corrugation'...
If you take your time and don't rush anything, I'm sure you'll do fine.