im thinking of buying some used injectors from ebay there from a 5.7 motor would these woork on my 5.0 and what kinda gain wouldi be looking at. also i hear they need new o-rings is this a big job to find o-rings also is it a big job to put them in

 

You would need a new chip to run the 22# injectors. Also for the trouble it would not be worth it on a stock 305 TPI.

 

slap a cam in it then worry about injectors

 

buying used injectors =