$275 is a great price, if in good condition.
I paid $300 for mine some time back & was delighted to do it.
No need to have the barrel solder checked. You can visually check the solidity of the joins along the rib on both barrels (never heard of a Stevens double coming apart).
Take a look inside the bores for rust or pitting, don't confuse lead or plastic buildup there for corrosion.
The safety should be automatic, goes on by itself when the action's opened. If it's not, it's been altered. Something else may have been done internally, too. Check for safety function by manually operating it, if it doesn't activate automatically. If it doesn't function at all, you may want to pass.
Using snap caps or once or twice fired empty shells in the chambers, close the action & make sure both triggers operate correctly. DO NOT DRY-FIRE IT WITHOUT SOME SORT OF FIRING PIN CUSHION! You can get away with it for a while, it'll eventually catch up with you. Parts are no longer made for those guns.
Note the barrel latch lever's position, it should be to the right of dead center (or to the right of the safety). If it's not, it's worn & should be replaced. The closer it is to dead center, the more wear's indicated. (General principle, some currently made guns come with levers pretty close to the centerline.)
Finding a replacement may be a problem.
Check for splits or cracks in the wood. Stock replacement may be a problem.
Check for a loose fore-end. That can be tightened up, but it'll cost you money to do it.
Good luck.
Denis