n!ck

hi im new to the forum looked on here a few times i have owned loads of yamaha dt125's i am currently building one with a friend and was wondering how easy the wr200 engine or dt200 engine fits into the dt125 any replys would be greatly apreciated my bike is y reg and what year of dt200 or wr200 engine i would need i have full dep system on my bike will i need to up the jets and if so what size? thx n!ck