Hi, I'm the Sean Corr guy referenced by the OP. I joined VCFED last year but had issues getting the account going. Anyway, I'm here now and look forward to contributing and learning!
As exidyboy said, the tape file was not a dump/analog copy but an OCR > heavy edit > load to Sorcerer > tape save. One of my interests is scanning old Sorcerer list printouts (Z80 or Basic) and using automated workflow, getting them running and saved in digital .wav format.
@tempest: glad you got it working in your setup. I also echo exidyboy's comments regarding the phantom code lines. I find that a bad Basic load will invariably LIST perfectly well at first, and then dribble down to meaningless lines. In fact, when in doubt, I sometimes do a LIST 30000 in Basic as the first step to see if there is any corruption. Not many Basic programs have lines beyond that region so it's a good initial test.