yx150 or 160 engine for honda replacement

Ok here is the deal I road race a takegawa 124Superhead but I will be doing a ton of rideing in parking lots local tracks and so on.. Dont mind spending 600.oo for the engine and would like 14 to 16 hp... I want something I can run in between races and not kill my race motor.. I know a ton about the honda stuff but very little on the China stuff.. I see where there are a ton of upgrades for the 150 engine. Simple cylinder and piston swap V2 heads and so on.. Now I dont wana put anything on this thing except an inner rotor kit and ride change the oil. So I want something close to reliable.. Didnt know if the longer cyclider of the 160 would cause me to have to raise my front end up some, its really lowered for raodracing.. How much hp does a good running 150 make and a 160 make.. And is there many hop up parts for the 160 as well.. Thanks for your input ill probably buy from a PM vendor but want to make the best choice.. Bikes a CRF 50 framed motorcycle