Mega 2560 instead of Metro 328

I am trying to get the Monochrome 2.42" 128x64 OLED Graphic Display to work per this example:
[Overview | 1.5" & 2.4" Monochrome 128x64 OLED Display Module | Adafruit Learning System](learn adafruit 128x64-oled-display)
And I dont have a Metro 328 so I was substituting a Mega 2560.
What more would I need to do, if anything, other than change the board ?

Nothing. Try and report.

I was willing to buy a metro 328 board but they are out of stock except for the $45.00 one.
The mega board will list what seems to be correct data on the serial display but nothing is shown on the OLED.
In my original post when I said “ change the board “, I was referring to within-the-code, selecting the board that is in use. Not changing the physical board.
Does that make sense ?
I need to find an easier OLED example.

The hardwire SPI port is on different pins on a mega. The I2C pins are also, unless you use the header pins labeled SCL & SDA.

According to the example, SDA and SCL are not used.

On a 328 your SPI pins are
10 = SS
11 = MOSI
12 = MISO
13 = SCK

On the Mega 2560, they are
53 = SS
51 = MOSI
50 = MISO
52 = SCK

so you will need to move your wires accordingly.

No. Selecting a board activates all board-specific changes to the firmware. As long as you follow the labels on the board for SPI and I2C your high-level code does not deserve any further changes.