Re: The problem probably wasn't the software...
The VAX architecture was pretty well defined + documented in the manuals (including the FP formats) - and those documents still exist (in my bookshelf and likely bitsavers.org)
Just yesterday I was scanning a couple of PDP11 FORTRAN (1975, so upper case) manuals, which will be uploaded to archive.org in a couple of days. And here is a VAX FORTRAN manual we did earlier.
(And we really deserve that cobwebs icon. It came out of the crawlspace under a flat on the Twente University campus. Icon as replacement for dust mask)