@stievenart then I am not good enough at searching.
Anyway I have learned from your contributions a lot. I will keep an eye and may start a project of replicating one of these serial boards. The one sided one is definetely special 
I had the same idea some weeks ago, just ordered the PCB’s as I was able to generate Gerber files from:
https://docs.arduino.cc/retired/boards/arduino-serial/
If you want it already checked and ready to order, I uploaded it to PCBway with some pictures of the board I received:
That is neat, I would love to see pictures of it assembled.
I have decided to give this a shot many thanks to @cararca3
The minimum order are 5 boards and as much as I like the project I dont think I need 5. If someone wants to have one from me (I will probably keep 2 or 3), I can help with that
Are you using an Atmega8? Which bootloader?
I never noticed before that the early boards including serial and USB v2.0 had in common the reverse order numbering of analog in pins. I think I would have to “fix” that on the silkscreen. I wonder if the pin numbering matched the very early core in the IDE or if it was a mistake.
I installed an ATMEGA168 from a Duemilanove, still waiting to receive some ATMEGA8 to install.
According to the Bootloader, I don’t know which one to use.
For old Arduino IDE releases, I found this repository:
I’m trying to compile version 0002 for Windows XP, but it’s so old that it becomes difficult to compile in 32 bits, at least for me 
I don't know much about the old versions of Arduino IDE, but it shouldn't be necessary to build the IDE for the purposes of obtaining the bootloader.
But if you are trying to do it to get a historically accurate IDE to use with the board, that is certainly a cool project!
As an alternative, you could use the relatively modern (and capable) Arduino IDE 1.8.19, but make it look somewhat like the older version of Arduino IDE. I created an Arduino IDE 1.x theme based on Arduino IDE 0003 for such a purpose:
This seems to be the bootloader.
That would be for the ATmega8, when you get one. You need a different bootloader for ATmega168.
(Or you can cheat and put Optiboot or urboot on either one, if you're not aiming for an authentic software experience as well. Although, without the auto-reset feature, that might be problematic.)
In stock at Mouser and DigiKey
Got them in AliExpress
BTW how did you receive the PCB’s sooooo fast? 
