502mpi upgrades
 

i am looking to upgrade my tired 502mpi this winter.i like the turn-key and go of fuel injection,and the reliabiaity.but mostly the fuel comsumption.rightnow i am getting around2.8-3.3 miles to a gallon at 40-45 mph.how hard is it to make a 500efi out of my 502mpi?cost?.i was thinking about just getting another block and making a 540 or a 572....maybe a 602.any food for thought out there?thanks

The difference between the 415HP and the 500HP is basically valve train.
New cam, larger valves, roller rockers, ECU remap.
Your Merc MPI is good to about 525HP without modification, so it will not work vary well on a big cube engine.