Where did you get the bits from,, for the dry clutch , Im guessing like me youve done a conversion? Mine rattles while you hold the lever in but once engadged the plates (let the lever out) there isnt a whine or noise at all in fact it sounds like a wet clutch (very quite), I only ask because the only thing i came accross when i did mine was that if using a 28 box on a 21 you need the primary gear from the crank as well, and visa versa for a 21 to a 28, if its 28 to 28 or 21 to 21 you dont it should all swap over? sounds like its the primary gears to me as in some of the situations you described the gearbox wouldnt be turning so its that end!,

only other silly thinks are the rubber seal on the tranny case? water/oil pump (did you put the washer back in? (for the water pump matt highlighted that there is a washer that likes to stick to the case when removed and if not aware it can fall off)...what about the push rod? did the bearing go back in (small one that sits at the end of the push rod? hope this help