Must I sleeve my block!

Over summer while my brother is away at Paris Island I'm pulling my motor and doing a complete build on it... I am hoping for 230-250 WHP after I am all done and tuned.

How important do you think it is for me to get a closed sleeved? I can't quite decide weather I want to keep my GSR block or just go for a B20...
How much does getting your block sleeved normally cost?

its over 1000 to get the block sleeved right, and for only 250 hp you wont need to have it sleeved,

to get 230 -250 on motor you are going to need to spin it real high with alot of compresion (13.0-1), you are also going to need alot of head work and dont be surprised when the valve springs you need to turn the high rpms wear the timing belt tensioner and camshaft out extra early, that kind of horsepower on motor wont be a long lived street motor

what he said is right, now you also didnt state weather or not you plan on keeping the C1 head, because that will be a factor as well, it will be easier to get that power on a pr3 style head, be it b16 or c5 head. and you dont need to be sleeved for that amount of power, i would suggest how ever just stroking it to 2.1 or so with 13.0-1 compression or 14.0.1 and rev to at least 10k rpms, wont be a cheap build, but you will get the power you are looking for, if not more.