What style of lug nuts are recommended for OEM rally's?  I have modern style chrome "conical" nuts (not acorns, though) and I was told by a Corvette mechanic some time ago that those are not recommended as he claimed they'd loosen.  Is that correct?  I've never had any loosening issues.  Should I really be using flat lug nuts?  

Someone else may have a different opinion but I believe the conical nuts are for the steel rally wheels.  The flat nuts are for the OEM aluminum wheels but even they have a conical section below the flat which engages the hole in the aluminum wheel.

TRUE!  YES, the correct fasteners are O.E.M. style. Same as for ANY steel wheel on G.M.

Ya..the steel rallies need a normal, tapered nut. All you need to do is see that the taper on the nut fits perfectly into the taper of the wheel holes. Some nuts/wheels have a different angle on the taper, so you do need to watch that, but any GM steel wheel of the era will use the same nuts.
Aluminuminum wheels are obviously different, and use different nuts than steel rims.

Thanks guys - exactly what I thought.  Don't know what that guy was talking about and a major tire store sold me those nuts specifically for those wheels.  But he's the same guy that told me the front rotors MUST be re-riveted or bolted to the hubs.  So I guess I'll take what he says with a few grains of salt from now on.  

Dave, there aren't any dumb questions.

I agree - at least not when it comes to C3's!