you will have lot of fun with it, just look at the by-pass hose just under the thermstat housing, if it`s 3in long it`s a 225 or a 198 ,if it`s an inch it`s a 170. just check out slantsix.org lots of good info on slant mods , especially oilling to help oil pump gear, it`s the only weak point when racing slants. did you check out the video on you-tube?