Are full boards of which I have designed a new PCB, based on the original scheme. I assemble it in my own Pick and Place Neoden4, what I wanted is to make a more compact design, with as few components as possible.
Another circuit, takes part of the original scheme, plus another circuit designed by me with a Kinetis MK66 microcontroller. All in a new PCB made by me.
The two circuits are old electronics, one based on a Z80 microprocessor and the other on a TS68000. Of the circuit with the Z80, I already made some changes, the original Z80 is DIP, I put the LQFP44, the Eprom was DIP, I have put PLCC32, the RAM was DIP, I have put SOIC, all the 74xx were DIP, I have put them TSSOP, the passive components were THT, I have put all SMD 0402.
OK, so you are already putting many hours into this, and can respin PCBs as needed.
If you look at a list
Cirtuit 2:
======
3 x PAL
1 x 74HCT240
1 x 74LS04D
1 x 74LS163A
2 x 74LS166D
6 x 74LS245
2 x 74LS273
2 x 74LS374
1 x 74LS74D
You might choose a split based on 'easiest PCB design' and IO pin counts.
eg Octal parts might stay octal CMOS, but change to better pinouts like 74HCT573
Then you can look at what is non-octal eg
3 x PAL
1 x 74LS04D
1 x 74LS163A
2 x 74LS166D
1 x 74LS74D
to see what makes sense to pull into a CPLD, and what might make sense to move to tiny-logic, placed where it is needed.
5V CPLDs are available, but as already mentioned, are trailing edge (but so too are your Z80 & TS68000
)
Digikey shows 35 5V CPLDs normally stocked, all Atmel part codes.
Which you choose again comes down to PCB layout, and you can swap PLD pins to help there.
You might choose a few ATF1504 in TQFP44, or fewer ATF1508 in TQFP100
You do need to design the PLD in parallel with the PCB, as not all pin choices will fit into the PLD
Addit: you may consider a 3v3 supply, and a 5V
tolerant CPLD - a Xilinx DOC claims this :
5V Tolerance CoolRunner XPLA3 devices are 5V-tolerant. Also, the XC9500, XC9500XL, and XC9500XV families are 5V-tolerant. Also note the ATF150xASV(L) parts can operate on 3v3 or 5V, and cheapest 5V capable 128MC part on digikey is
ATF1508ASVL-20AU100 128MC 20NS 100TQFP 771 - Immediate $4.42000 @ qty 1