Jim,
First of all its your car and you do as you please with it!
Some people questioned my insanity when I cut up my Z/28, pretty much in the condition you described, for SFC and DSE style rear crossmember. I haven't minitubbed it yet but I will in the future.
My thinking was: there are so many restored Z/28s that the world doesn't need another one, but there aren't that many PT Z/28s
Same thing with yours, the 69 convertible is a hell of a good looking PT car and restored 'verts we have more than our share of.
Keep going.
Jan