I made semifinal version. It includes MOSFET level translators. (It might become final after successful tests)

I wanted to include integrated level translator, but they are expensive (MAX3002) or hard to find (GTL2003) or reported faulty (74245 with AVRISP mkII). There might be some conspiracy: none of the above have pinout compatible with another!

I chose BSS138 MOSFETs because I inspired myself with Sparkfun's level converter tutorial. I believe, that generic level converters, I have, have the same transistors (or something with worse parameters) and they work properly, so it's worth a shoot.

New board is bigger than 1.0, but still pretty small ~45x90mm (something like ~1.8"x3.6").

I ordered few PCBs from Chinese manufacturer. They should arrive this week, I'll test them ASAP.

Oh! The "b" in reversion means, that there was 1.1.1 in the process. In 1.1.1 I used autorouter, which did the job I wasn't satisfied with. Then I saved it with different name, rip up that mess and routed it manually.