need help shoving a CPU in a pc it's very much not intended to go into

Around six months ago (and luckily before the whole ram shortage) I managed to scrounge up enough money to build this monstrosity of a machine, based on what I thought was a lenovo thinkcentre m700... More on that further down.

The whole mod works wonderfully. But the problem i'm facing is that the poor i5-6500 it came with just cannot keep up with what i'm doing with it and bottlenecks the whole machine.

Without any mods. The Best CPU i can put into it is an i7-6700. Which is still a 6th gen CPU... But it's still about 70€ where I live. While for some reason I can find a lot of i3-9100. For 20-30€. Which from what I understand are B0 stepping chips and don't require pin modding to be used. And should still be a good upgrade.

The last problem was the BIOS. The bios on this machine is not meant to support such a new chip. But I remember reading people having success with a program called "coffeetime" to shoehorn the microcode to use newer cpus.

When I went to sanity check what the machine's bios said. I found out it's a actually an m800. Not an m700. This raises a problem. Since it's chipset is a q150. That has the problem of having a stricter/ more in depth Intel ME. That from what I managed to find requires somekind of bypass.

Do you think this is still feasible to do? And do you know if there is any safe source for coffeetime / some guide to do this mod by hand? Since having a random software that I can't read the source of modify the bios of my machine feels a bit iffy.