Very Difficult Question...

[induction]

yes these heads will fit your 289 block but without "headwork it's a bitof a waiste of time. also th 351 willfit without too many mods, it all depends on what you want /where you need to be c/o torque vs. horsepower. Now another option isto stroke a 351 to a 427 this involves .;new rods ,crank balancer headwork ect.an a big wallet to the tune of 3,500 bucks. My sugestion is to use the 289 block,port the 351 heads ad headers large exhaust, port a victor Jr. intake, an for a bit of umph try a hole-shot NOS unit. This tends to work well for a day to day car with the bonus of that mighty stop light launch. all in all about $350 without the nos unit. E-Mail me with the location of my new Cobra
thanks & let us know how it turns out.