O.K. mrleesimpson can I ask why you class that as the most important issue regarding his site?
The search engines will index the first 125 characters of the alt attribute, which will mean all his text should fall under this mark and thus be indexed, ok the value of it will be devalued but they will still be indexed.
However by not consoladating his equity and removing harmfull tags, such a mutilple h1's, he will be penalized!!!! be it his equity may be halved, thus rankings WILL sufer, plus content duplication penalty and a filter all joining in on the spammyness of the tags.
This is by far the greater issue here regarding SEO and his site, the SIFR is an important issue, don't get me wrong, but not the way forward.
Fixing the penalization issues is the way forward, followed by the SIFR as an added bonus and a good SEO policy.
Otherwise what's the point?
He's still going to be penalized, regardless of if the text is indexable out side of the alt attribute via SIFR.
Jaz