The other thing to remember is that the transom on the new ones may have been beefed up a bit since that one was built - Mine is essentially the Grandaddy of the Ocean Pro 5m , but is only rated for 60 Hp - the new ones are rated somewhere around the 80/90Hp mark. Also if you're planning on dropping a shiny new 4- stroke on the transom the engine weight may be an issue too. Check the builder's plate!
As for the tubes, they use Hypalon for a reason! I can see no issues with the sunlight - My current boat is a 1979(ish) build and apart from a leaky valve holds air nicely - and it's spent most of it's life outside & afloat. Having said that, I'd second the "do the soapy water test" - then you know for sure.