i havea 89 chevy c/k with a305 , i replaced motor and put a 350 . iknow that the prom has to be replaced do the tbi injectors have to be replaced .
Not sure if the injectors need to be replaced. My guess would be no, but you might need to replace them. External dimensions and bellhousing should be the same. Should be a fairly straightforward swap.
I did this about a year and a half ago in my 88 c1500, i did not even change the prom, i just did a direct swap with the new motor. injectors should be the same from a 305 to a 350, the only thing is 454 has bigger injectors. I rebuilt the Throttle body but changed nothing and it runs great and has plenty of power.