coming from a SHO owner, im confident in answering this. simply enough, you need a new clutch set. the fingertips on the pressure plate have prolly snapped and worn the face of the TOB and now the fingers are hanging onto the TOB.
hopefully the original owner took the SHO in for the clutch uograde. 89 and 90 came with a 9.25" clutch, the TSB upgraded it to a 9.75" clutch. this can easily be checked without removing the transmission, but starter removal is required. a new 9.75" clutch set can be bought at for favorite auto parts store for around the price of $270. it comes with a pressure plate, clutch disc, throwout bearing, and alignment tool. if it is the smaller clutch, youll have problems finding them, though it is cheaper.
with the new clutch set, youll more than likely need to remove the quill sleeve on the trans inout shaft quill. while some have had issues removing it, i have not. just pull back on the tangs, and twist and pull,
as for the clutch adjustment, the quadrant is notrious for not holding its position when adjusted. i had to get under the dash and engage mine using a screwdriver.
though the site is down right now, check shoforum.com. im there with the same user name as well.
any other questions, feel free to PM me.