Mine is an '84, so I already had a fuse block with the ATO style fuses in it. I simply kept that, but removed and cleaned and soldered the connections. I also purchased some of the plug-in connectors to add additional circuits. You can check here for more info:
Fuse Block Connectors
In terms of a wire run list, or schematic, I used the stock CJ wiring diagram, and then simply added the additional circuits I needed (dual battery, OBA, LED spots, power outlets, audio power amp, extra speakers, inverter, 7-pin trailer plug, map lights, towing mode, power for lockup torque converter, neutral safety switch on shifter, ECM, keyless ignition, heated seats, digital gauges, electronic speedo, etc).
eBay has some listings for NOS fuse blocks/harnesses for around $100:
CJ Fuse Block Another CJ Fuse Block
To use an actual CJ fuse block, you would need the square hole in your firewall where the fuse block mounts under the dash and has the bulkhead connector that connects in the engine bay side. Not too hard to do, but you'd have to cut a hole to do it. Your other option as mentioned earlier is a generic wiring harness. You could get one on Amazon for $40-$50:
Generic 12-circuit harness, or a bit fancier but still under $100:
Another Amazon Harness
If it were me with an older CJ that had the style with the glass fuses, I'd replace it with one that uses the ATO fuses (I did that on a prior '77 I had). If I were in your shoes with an older one that had no fuse block at all, I'd get a CJ block with the ATO fuses and wire it up like a stock newer model. Plenty of wiring diagrams and help that way. Sure, add additional stuff as needed (lights, etc), but newer stock to use existing parts, diagrams, and other people's examples. To me, that would be worth $100 or so to get one. Lots of people have used Painless or EZ and paid $300 or more for brand new. Great if you can/want to spend that money. But if not, get a used one and work it over to meet your needs. You've already got a GM engine swap (that's what I have), and I assume different alternator and ignition setup with that GM engine. But easy changes to a stock CJ harness. Be a lot easier adding or servicing in the future with a CJ setup, even if it's from a newer model. Just my .02 - well .05 now since no more pennies and we're all rounding now.