I wasn't going in the early 80's but did see him when he returned to link up with Shawn at Sheffield in the Maurice Ducker years. From videos I have watched I would agree you probably had the best version of him when he was very young and the bad living didn't have so much of an effect due to his youth, when he came back he was still brilliant but probably 10-15% down on what he could have been due to a poor lifestyle.
I was fortunate to see lots of brilliant riders but for me my top five natural talents in no particular order have to be Cowboy Cook, Kelly Moran, Mark Loram, Henka Gustaffson and Darcy Ward.