Hello Mark!
As an quick decision for your situation - please do the following:
1 - export product with fields
2. Import products with expressions
use this Function - REPLACE
Syntax:
REPLACE(str,from_str,to_str)
Returns the string str with all occurrences of the string from_str
replaced by the string to_str. REPLACE() performs a case-sensitive
match when searching for from_str.
3. Here we go... looks at screenshots - I hope it works for you :-)