i've been looking over the campag bits in the pic to try and guess the age of the parts, here's my thoughts and i'm happy to be corrected cos i'm guessing from memory!!
i had 95 record 8 speed on my cougar (bought brand new), the ergolevers you have have the cut out on the inner gear lever which i think was the year after mine which don't have that cut out, so 96/97 i think, then they changed the shape of the lever after that but i think your shape was the last 8speed record. the cranks i think are the first 9speed record though, the 8 speed record cranks (which i stupidly sold) looked very different, so i think the cranks and brakes are 98ish. the front mech looks later aswel.
i think it should be a complete 9 speed built bike but when someone has come to sell it they have kept all the 9 speed bits they wanted to swap to another frame then rebuilt it with the rest of a 8speed group, the idea being that the new frame they got used a non campag chainset and brakes etc so they just needed the 9speed bits, chain,cassette, wheels, ergo's etc.
as far as the wheels go, i have a set of vento's with 16 spokes, using the hpw hubs which used straight pull internal style spokes so it suggests that your wheels are earlier than mine but that makes sense coz i got my wheels a year or so after i got the bike (i ran record/open 4cd to start with) so i think mine are 96/97, also i remember the shamals the same model year as my vento's were 12spoke!!
so to summerise i think your frame is 99/2000 but the wheels are 95/96, the 8speed stuff is 96/97 and some other bits are 98ish
but that's going from memory.
bloody nice machine though.
here is a (old and scanned) pic of my cougar as it was when brand knew in 95 to compare the campag, it was boardman copy, slx tubing in gan colours but with full 95 record