Kicking around ideas

So im putting my R together but when thats all said and done id like another project. Im thinking cr500 bike but maybe a 4 poke bike, so what do you guys think of modding a 400EX frame for a YZ or CRF motor? Is it doable on the cheap and stuff. Also what about the CR500 is there any long term reports on these things in a quad frame, I know alot of people had issues on vibrations and stuff. I know its pretty scattered but Im just kicking ideas and wanted some input from the pros on these things. Id like to stay away from the aftermarket frames because I dont have that kind of money espeically after I get my R build done.

Only thing i heard about the cr500motor is it packs more power than hte yz motors and viberates alot so you need to lock tight every thing. The yz motors have better overall power cause the cr is all top end.
To mod the frames it will cost around $200 to have some one do it or cost a couple dolars to d oyour self

go with a yz motor . takes major frame mods for just the exhaust on the cr. and for a 400ex frame u need to change bottom motor mounts and upper motor mounts. pick up a diff oil tank make mounts for it remove the stock oil tank position and put radiator mounts on. there will be other small thing but nothing big other than what i listed and some of that isnt big

Well I went to school for chassis fab and I can MIG and TIG weld, so Im not worried as far as fab work goes, just more towards ease and cheapness of the whole project. And I want something thatll fit good and look clean. I dont want a pile of parts mish mashed into a frame with no room to work or anything. Id really like to do a CR500 frame but the vibrations working things loose and causing stress cracks scare me alittle, and the fact that the right motors are hard to come by.