This is a great kit, and you’re doing a fine job. Despite your problems, the red finish looks great and looks just like Guards Red to me. I prefer using pink primer for red cars, as I have had the exact same problem in the past.
I used to own a 1:1 of these about 15 years ago. They hit rock bottom prices back then. At that time I picked up a few Hasegawa kits, and the Revell kit (which is the same tool as the Hasegawa). The Italeri kit is a different tool. Hasegawa also make a 968 Porsche (which is the later version of the 944), and many parts are interchangeable. I intend on building a 944, with 968 wheels as a replica of my 1:1 car some day.
One thing I learned from the 944 community at the time, was that the non-sunroof cars were preferred as track cars. If you are building as a track car, then you have the best kit to begin with, but if you’re building a street version you can ‘pinch’ the rear seat from Hasegawa or Revell kit.