I assume you mean the original late 60's early 70's Ranger 26? Not the Mull design of the 1980's.
These were pretty well built boats but 40 years is a long time. I haven't heard of Rangers having worse corrosion than other iron keel boats of the era. Unless the owner can show you paperwork of replacing the keel bolts
, just assume they need to be replaced. The new bolts will be good for longer than you'll own the boat
. Same with the stanchion bedding. Unless the owner's already done it, assume they have to be unbolted and the bedding replaced.
The wildcard is rot
in the balsa cored deck
. Don't be scared off by a few small soft spots - very few boats of this age don't have some. But big rotted areas are simply uneconomical to fix on a low price boat