Seems to me the second piece of paperwork was the primary reason it sat unsold and unused for so much of the last seventeen years - inadequate documentation on the boiler build. Most operators, and need I say insurance carriers, won't touch a boiler without proper documentation.
Regardless of the qualifications of the manufacturer (as touted in a post below) it would seem that regenerating specifications which don't exist from a job done in 1988 would be pretty difficult. I really question whether they can get around that despite all the assurances. If I were the underwriter I wouldn't touch it with a ten foot flue.