Refinishing a Pre-27 would almost certainly hurt its value especially if it's in 80+% condition. You have to understand, to a collector, an original finish with "honest" wear is far more desirable than a perfect refinish and a pre-27, particularly with the less common 5" barrel, has significant collector value. If you have no sentimental attachment to the gun, you could probably sell it to a collector for enough money to buy a later 5" M27 with a better finish and still have money left over.
Smith, and Wesson, and Me. -H. Callahan
Well waddaya know, one buwwet weft! -E. Fudd
All bad precedents begin as justifiable measures. -J. Caesar