An S1871 bayonet is a great (but somewhat expencive) choice. It was widely used with the Gew88. It is a huge, impressive looking bayonet.
Then there is the S71/84 bayonet and a lot of ersatz bayonets (The ones with the dual radius muzzle rings.
Here is a common ersatz type mounted on a gew88.
And here... With S1871