I made that one years ago. I just swapped it over from the 2.9 that was previously on the car. I'm sure you could make what you have work with a dremel or a file....it just needs to block a hole.
I used 1/8 pneumatic push lock connectors on all boost reference lines. You can find them on Amazon. I had and have alot of the fittings and lines already in my shop, I did need to find some fittings that I needed and everything was on Amazon.
I did exactly what your thinking with the doorman. My blade was cracked also and I swapped blades with my original one, it fit perfectly and works like the original. The doorman is now a backup if needed.
Sounds like clutch. What's the disc material in that clutch? Non organic clutch materials can make a high squeal or chirp in first on take off like your describe. See if it does it after you put some heat into the disc's. Slip the clutch a few times, some times the disc surface can glaze over...
Good eye! My Capri is my Drag car, I set it up to run in NMRA/NMCA back in the late 90's early 00's. It's a SVO block 414 ci stroker with a face plated Doug nash 5spd, I shift around 8200 rpm. Now it's on a mechanical alcohol set up. Its fun but life gets in the way some time.