Gabe...I just finished reading your 'blog' over the past several weeks. You and your avocado went thru alot!! Nice car! As for making your avocado more comfortable during summer and winter I highly recommend to do what I did to my red 930. When I bought it nearly 20 years ago it had neither AC nor heat and drove without either for 10 years. Then I decided to add electric AC (my car was missing everything needed for proper AC). Now my wife is happy go for a ride/trips during the summer months. Several years later I added a Webasto parking heater since there's no heater box on the headers. It works well even when the outside temps are in the 20's F. Here's the link on how I added the heater.
https://forums.pelicanparts.com/911-930-turbo-super-charging-forum/1136788-webasto-air-heater-installation.html
There are several other threads on how others added the parking heater in different locations. Just thought I'd help out regarding lack of AC and heat.
BTW, regardin your avocado...I'd sell the GT3 engine and stay with your current 993/G50 setup. I think you worked out all of its bugs and it's just not worth the headache and time to make the GT3 work without any flaws. Also, congrats on being a dad!