[RioRico]

Yes, you'll find that 135's are usually much more common and much less expensive than 100-105's. Be aware that front thread sizes are somewhat significant. If both your 28 and the 135 have 49mm threads, all you need is a 49-49 reversal ring. If the 135 has a 52mm or 55mm front thread, you will need a 52-49 or 55-49 step-down ring to match the 135 primary to the 28 secondary.