Pin interrupt config

Hi, I'm rewriting the GRBL library for RAMPS and changing the PINS, however I'm lost on the interrupts ... Is there any guide/info on how to double check I got it OK? I did highlight the questionable settings in red.

Original code

define LIMIT_DDR DDRB

define LIMIT_PORT PORTB

define LIMIT_PIN PINB

define X_LIMIT_BIT 4 // MEGA2560 Digital Pin 10

define Y_LIMIT_BIT 5 // MEGA2560 Digital Pin 11

define Z_LIMIT_BIT 6 // MEGA2560 Digital Pin 12

define LIMIT_INT PCIE0 // Pin change interrupt enable pin

define LIMIT_INT_vect PCINT0_vect

define LIMIT_PCMSK PCMSK0 // Pin change interrupt register

New code - changed to PORT E

define LIMIT_DDR DDRE

define LIMIT_PORT PORTE

define LIMIT_PIN PINE

define X_LIMIT_BIT 5 // MEGA2560 Digital Pin 3

define Y_LIMIT_BIT 4 // MEGA2560 Digital Pin 2

define Z_LIMIT_BIT 1 // MEGA2560 Digital Pin 1

define LIMIT_INT PCIE0 // Pin change interrupt enable pin

define LIMIT_INT_vect PCINT0_vect

define LIMIT_PCMSK PCMSK0

#define Z_LIMIT_BIT     1 // MEGA2560 Digital Pin 1

Do you REALLY want to use one of the hardware serial pins (for Serial) for this purpose?