A/C Engine Upgrade kit for '68 Dart

I'm wanting to get the A/C working in my '68 Dart. I've redone everything under the dash, and have all the old components from under the hood except the compressor and mounting brackets for the compressor due to going from 273 to 440.
I emailed Classic Auto Air and they want $700 for their universal kit, the only Mopar dedicated kit is for the E body. I've also looked through Bouchillon Performance's website.
I'm looking for feedback from people who have upgraded their factory A/C car and any other options out there. I would prefer a kit with good instructions because I don't know much about A/C, I have never even charged a system before.