The problem... Your small end has failed Prematurely.

The most likely reason for your small end bush failing is lack of oil or/and over heating.

The Stormer small end bushes have a 10mm (.375") diameter oil hole drilled in the end of the rod.
Make sure that the bush has not turned, shutting off this oil hole.

We have been running our own bikes on Silkolene Casterene R40 @ 32:1 for many years without problems. We can highly recommend this oil to you.

If you are experiencing small end problems and are using a modern synthetic oil, don't forget that these modern oils are designed for use in engines where the temperature is maintained and controlled at a lower level by liquid cooling.
These oils are not going to offer you the same protection that a bean oil will.
So before you seek a complicated solution by fitting needle rollers..... check your oil. It may be as simple as that.

Make sure you are not over revving the engine, particularly if it is a 370 or 410. Keep the gearing on the tall side and make the engine pull hard.