Ok heres my take on my 85' CR500.
i reckon the "beast" thing is a myth, yes they have a real strong engine and the 68 hp thing has been "claimed" many times but i reckon its a great engine, anyone that rides/has ridden a big bore knows you don't need top end as you should mostly be short shifting in the mid range area anyway. you don't need to rev a big bore out, that's for 125's and 250's which demand a different style of riding. i have offered many experienced older riders rides which knocked the offer back only to hear " it's way too much for me" i say "it's up to you how fast you go" and that's true of every bike.
i love mine and there is only a few times it has given me moments when it has hooked up when i didn't expect it, over all on most tracks it tends to spin the rear rather that haul the front skyward. if you didn't need to get from the pits to the line you could take out first gear as mine is a 3rd gear start on most tracks depending on the drive away from the gate, it pulls it easy ( most 5 spd big bores will anyway)
mines a stock engine except for wiseco piston and pro-circuit pipe, i rode an 88' model that had lots of other gear on it ( v force reeds, porting, pipe etc) and i found it way too punchy & harsh for me.
YZ250H and others happy to let you have a spin any time, just ask me if you like.
Brad has posted a similar take on his 85' before as well sometime back.