i found a crashed hornet600 with cracked frame.front end is kaput engine is running but not sure what state its in.am thinking of putting the engine in my NC23 if possible but will the cost be worth it? ideas how much in USD?

BTW the hornet is cheap

Would the cost be worth it? Thats only up to you to decide.

Is it possible? Simple answer is - don't know, I've not heard of this myself. But that doesn't mean it can't be done as anything can be made to fit with the right sized hammer. This sounds an interesting idea however, any idea how the engine mounts line up?

Should go in the hole as theres more space in the 23 than the 29 and that just about fits. It's not gonna be a straight swap.

You will have to get some CBR600 F2/F3 carbs tho as I'm sure the hornet is side draft but I could be wrong.

i believe there will be some engine mods. dont think the engine mount straight in.
the carbs are another issue, if thats the case then more dinero needed to finish this equation

will consult a reliable mechanic

i think you find the frame needs to be modded to take the 600 lump, was a fair amount of info on the old forum.