A\C heater box vs non A\C heater box

As post #7 says, these reach around do it yourself harnesses, are not for everyone, and regretfully, you just found out why. Reach around meaning avoiding buying an orginal replacement. M&H orginal replacement harnesses in all 3 of my cars. One is an A/C car , just like yours. The fuse box is supposed to be somewhere else, not at the bulkhead connector. Sorry that this isn't what you want to hear, especially after spending good money on your reach around.
Yes, you can buy an aftermarket A/C heat system, but, they are for a car w/o A/C. Your firewall is different, but it can be done. No free lunch. Your old system can be rebuilt, but hard telling what you have and don't have. Kind of a can of worms your in.