Looking to do engine swap (upgrade).

I have a 1989 lt250s Quad Sport. Not enough power. I bought it for $400, absolutely nothing wrong with it.

I have the following engines to choose from:
[ul][*]Late '70s early '80s Suzuki 500 twin 2-stroke (might be a triple) out of a street bike.[*]Mid '70s Yamaha 400 2-stroke single (enduro)[*]'79 Honda XR 500 4-stroke single (bored to 530)[*]Late '70s CB360 street bike.
[/ul]

All engines run, prices range from $100 to $300.
I am prepared to do minor or major mods to frame. I am just looking for some brainstorming Ideas from you guys. What do you guys think? Will any of them even work allright? Let me know!

Chris

 

keep it light and the engine in an offroad class an engine is built to do its job id say the 400 2 stroke would be the engine for you however u might wanna check to see what after market goodie u can get for it i had an 75 it 400 yamaha and couldn t get anything for it not that i cared i just got it cheap 80 bucks and it ran soo..
86 4trx&atc 250R