hey guys i have 289 and i was looking to get a little more HP out of it for cheap and i was looking around i seen that if you throw some 302 heads or even 351s it will increase engine's out put if so how? and how much HP does it gain? Thank you

 

Heads meant for a 302 or a 351 will drop the compression and lower the power of your 289. The 289 has less stroke than either the 302 or the 351, so heads meant for those motors will have larger combustion chambers.