A duneable overide can be ridden like a OEM trans.. but.. If you backload them over 8k they will prematurely wear the shift forks. I like to call them "overides for beginners" because they can be backloaded where a standard overide can't.. 1 oops and you could be back on the trailor. Lockups are usually needed on 80+hp motors..alky or not. When you get up in the HP and you use a lock up it makes it hard to shift under power. So thats when people usually opt for a overides. I'm sure you could use 6 of the super HD springs to get the clutch to hold without the lockup.. but that clutch pull would be HARD!. Most people that use overides have drag racing pretty high on their list of riding types. On a 2-5 overide first gear isn't removed, its just not overiden which means you have to clutch 1st to 2nd and then you can do clutchless shifting.
I use a duneable 1-5 overide and I'll never go back!