Welcome to the forum.
Nothing wrong with Zodiac Classic - it's a very capable SIB. Welded seams, PVC (Zodiac use Strongan Duotex material). Personally I like the HD version (aluminium floor).
Depends on when it was made and how well it was looked after. On the transom there should be a build plate with year of manufacture - so that's a good place to start. No reason for that to be missing as it's riveted on.
Goes without saying, see it in person, viewing condition and pressures, etc. Wear points can be the transom, especially if glued areas are opening. This boat also has an inflatable keel tube, again a wear point used to be the fold near the transom.
I used to run a Zodiac MkIIC GT with a Yamaha 25hp - and it was rated for 40hp. Not sure where Zodiac think you're going to source a 35hp from - according to their data sheets?
https://www.zodiac-nautic.com/en/boa...sic-mark-ii-c/
Plenty of knowledge on Excel and Honwave.