Looks like a good choice on the heater. Still have room for the wiper motor? It's hard to tell from the photos. I'm currently waiting on a complete wiper motor , washer & related parts as part of my 66 c10 re-wire project, so that immediately came to mind.
Since I live in Florida I'm going to do the full A/C & heater kit but will retro fit after I've got a up & running truck.
Your project is looking good. Thanks for posting.