Magnum Intake on LA engine?

Bill if you use a 318 you could just use the magnum heads. They sell coversion pushrods and you will also need AMC style tappets for pushrod top end oiling. The 318 has hydraulic valvetrain and the larger bore will give less shrouding on the larger intake valve. 318's are cheap and not hard to find plus more cubic inches will make more power. Nothing wrong with a 273 but they are very limited as far as how much more you can get out of them.