year breaks on 225 please

You will likely have to lengthen the distributor and alternator parts of the harness and possibly the ac wire or wires as well as the slant 6 is a bit longer than the V8.
Yup that's what I had to do on my 85, my wiring was an "extreme" **** show as well, for starters the big "hot" off the alternator changed color and gauge 3x in the length of the/6 valve cover. Just twisted together and crudely taped, not even a crimp or wire nut (like I've seen some idiots do) one of these twisted connections was draped 1/2 " above the fuel line from pump to carb, with bare strands "escaping " the tape job..... It's a wonder this thing didn't burn to the ground.
I found a 84 D350 with a 360 in the yard that I pirated the wiring harness from and used that. Connection wise the only difference was 1 or 2 wires for the wipers that went thru the bulkhead were plugged in, in different holes in the bulkhead connector. I had both the 84 and the 85 wiring schematic out in front of me on the kitchen table, as I went thru that harness....
Now back to regular scheduled thread on differences in /6s year to year