No More 95 Octane Non-gasohol. What Now?

[PMK]

I have been following the LPG/CNG threads with interest, but wonder what my other alternatives are.

I have a '91 Civic. The recommended fuel is 95 octane. I've been running 91 for a while with no hint of a problem. No run on, no knock. The timing may have been set back a bit by the mechanic but the car is peppy - no complaints about power. But I wonder if I am living in blissful ignorance potentially causing serious engine problems, or does the lack of knock, etc. indicate that the engine is burning 91 okay?

How about continuing on with 91 but changing to a thicker head gasket if one is available?

Also, what would be involved in converting the car to run gasohol? I know that the alcohol affects rubber products, but just where would those be likely to be? Fuel line couplers, fuel pump? carburetor?

Any thoughts or suggestions are welcome.