new project using 7 segment displays

im a great believer in the right parts make a project easier so im looking for some advice on what parts to use.

I will be converting another peltier wine cooler into a egg incubator. the original one I built I used a 40x20 display and 4 I/r buttons behind a plastic screen. It worked great but the display is hard to read at a angle and the buttons can be a pain to find in the dark.

So now my wife wants me to build one for her friend but they want it simple so no lcd etc.

I figure I need 5 led 7 segment diplays.

2 x 4 digit
2 x 3 digit
and 1 x 3 digit or a clock style led display

I am considering using the pre-mounted 8 digit (with a built in max 7219 chip) and cutting the trace to the 5th digit then painting over it instead of using a 4 digit and a 3 digit as I can not find cheap 3 or 4 digit pre assembled boards or do you think that buying the parts separate would be a better idea.

Is the max 7219 chip still a good chip to use?

I plan to update the displays every few seconds

I would like to try to find a board where the leds can be removed so different colors could be used but that seems a expensive option and ive noticed that some parts are not the same as the pictures posted especially on ebay.

other parts used on the project will be 2 x dht22 temp and humidity sensors, mosfets using pwm , 3 x 4 button pads and a dual relay board. so im planning on using a mega.

Is there anything im doing that looks wrong or old fashioned?

So you need 20 digits total?
Buy a bunch of singles, mount them up in groups of 2,3,4, and wire them up in groups of 8/8/4 to three max7219s.

Select common cathode parts for easier use.