Fred I concur restoration costs are always way more than you estimate. Plus the correct parts are getting harder and harder to find.
I spent over a year and many hundreds of hours documenting the race history on my GTA. The SCCA Archivist Pete Hylton helped plus reading lots of old AW (competition Press) want ads plus interviewing all past owners.
It is tedious work but worth the effort.
I know i own several cars. Did several restorations. 100 000 $ is on the conservative side for a restoration.
My brother by the way finished our GTA will ask him to send some pictures.