i have a motor from a 1999 explorer i bought mostly for the heads and intake but it has low milage (35k) and my 1991 mustang gt 5.0 has high milage (160k) i want to use the whole explorer motor is it better than a mustang motor i was told to change the pistons and cam im defintly going to change the cam any recomendations and should i change the pistons what should i use if i do change them does anyone know the compression ratio for a explorer motor sock