Which SMBIOS should I use?

Hello,

The Vanilla guide suggests using iMac19,1 for Coffee Lake CPUs. I have an Intel i3-8100 and an AMD RX460 GPU. Is it not ideal to use iMac19,2 instead because it also uses the i3-8100 CPU? Or should I really stick with the recommended iMac19,1 for better results?

Dumb question as well, does monitor size matter? I mean all the iMac19,2 devices are 21.5" while the iMac19,1 are 27". I do have a 4K 27" monitor.