I owned two. A 73, and a 74, almost bought a "creamsicle" 74 2.0 Wish I did... Be different... Buy a 9146 chassis stiffening kit, upgrade the brakes to 911 S, and then find a 928 S motor, and drop it in, you won't be sorry.. It makes me sick to see people put LS Chevy small blocks in these cars. I would keep it pure. There are a few 928/914 conversions on RU-vid. The only problem I see is that the water pump on the 928 sticks out a little too far far, but that is easily rectified 5 blocking off the original location and using an electric pump to feed radiators in the front. That way you don't need to cut the firewall. These are great cars they deserve the status they never got before
Kudos to you for going all in on the repair. That’s a gnarly place to be fabricating for sure. As you implied, I would do my best to get the welder dialed in before doing too much more. The spots still look quite a bit cold to me. Should you ever decide to sell, any patch would be noticed but cold looking spots might give the wrong impression. Nobody wants to burn through but you have some room to go up in heat IMO. Keep these videos coming!