Hi,
Great! TR250 are a neat car and rarer than most other Triumphs. I think it's a great combo, the 6-cylinder engine with the earlier "retro" Michelotti body style.
Hopefully the car is in great shape and the following is not to scare you away, just to give a general guide where to look. (Oh, and I strongly agree, get Roger Williams' book... In fact his other one for TR4/4A would also be very helpful, particularly when analyzing the suspension, body and frame which are virtually identical to TR4A IRS.)
Body issues are about the same as TR4/4A. The most likely areas of rust concern are those subject to "splash" around the tires: up front check out fender mounting edges along the top (up from underneath and from inside the engine compartment), the splash panels immediately behind the front tires, the lower/rear front fender and the rocker hidden under it. At the rear look also at the top edge (up from underneath and from inside the trunk), check the B-post base (really need to peel off the vinyl trim to do this).
Inside the cockpit, look at the floors under the carpet. Also check the steering column for any wobble, the mounting bracket at the firewall sometimes breaks loose.
The frame issues would be most similar to TR4A. Look for a wider gap at the top/rear edge of the doors. This indicates a "hump back" frame that's especially weakened. The IRS frame usually tends to rust from the inside out, from the rear first, toward the front. So especially check out the rearmost main frame rails. Also look closely at the front suspension mounts, right at the inner/lower pivot points. The brackets welded to the frame really should be reinforced, were too weak to begin with. The rear differential support pins also tend to crack loose from the support bridge above (best repaired/reinforced with the body off), with the right/front pin being the most vulnerable of the four. The rear/upper spring pads can crack due to age and stress. The mount at the rear of the gearbox can also crack loose.
Those are the major areas, that come to mind right offhand.
Hope the car checks out and you get it! Let us know!
/ubbthreads/images/graemlins/cheers.gif