I figured it will take 37 different parts to build one memory cell (complete with three-state output), and one 16 bit register will require up to 600 parts to solder, and I see it will be a hell of work and time to solder it together and make it work properly, so the registers for display will definitely be repurposed if I will build a CPU.

The memory cell consists of data latch with additional ~set and ~reset inputs and tri-state output stage. The latch is made of 2 2NAND and 2 3NAND dtl gates, each of which have three resistors, one LED, one transistor and number of diodes equal to number of inputs as their constituent parts. The tri-state output stage is made of 5 npn transistors and two resistors.