I have some experience with a blown street car and they can be a challenge. I dont have all of the answers but I can share what I have learned with my car. First let me say that it is probably not any one thing you are going to find that "fixes" the overheating problem, everything is a balancing act and when everything is out a little bit you have problems. Even though it may look like a shroud would not help, it did with my car and there is not much of a shroud there. Second Ido not have a hood so I doubt that is your issue. I think Cnuts advice to do a through flush and clean is a great one and then see what you can fab up for a shroud even if it is temporary would help. One thing that has not been mentioned is tuning of the engine, I know on my car ignition is very sensitive, the blower seems to magnify every small issue. So check plugs (I would replace) wires, cap, rotor, coil, make sure everything is in great shape. Then on to check timing, not sure what yours is set up to run, but if you have a race track tune up in the car and you are trying to run on the street, does not make for a happy motor.

I know what you are going through, I inherited the 27 from my Dad two years ago and it took a few months of adjustments to get it running like I knew it should. Keep after it and enjoy the process.IMG_20170606_113750.jpgIMG_20170606_113729.jpgIMG_20170606_113757.jpg