Does anyone know if a non railed 228 will fit in a Safariland 6004 made for a railed model?

The fit should be fine. Safariland holsters retain using the barrel (plastic post in the holster inserts into the barrel), sides of the slide, and the locking mechanism into the top of the slide / breach. Since the rail frame is slightly larger than the non-rail, there should be a little extra clearance. Safariland light holsters will even retain a pistol with no light on it. I wouldn’t expect any issues with the fit.