You make valid points and I'm posting here because I want the critical feedback, so here's my response.
Nearly all of my challenges are because I refuse to go with a high rise hood. As such, I'm working around engineering challenges of height and space and solutions to these challenges are parts replacements and/or alterations of existing parts. All of this is expensive.
All of the articles I read say the Box R is farrrrrr superior to the R-Series in airflow. Even porting the R-Series would net minimal gains as compared to an out of the box Box-R. Hell, in that article I posted, the Miata guy picked up 33 horsepower on his 331 with the Box-R over the Series R. 33 with no other mods!
I plan on having the car long term, like decades more. So why would a few thousand dollars matter in 2026 if the car jumps from 400 rwhp to 430-440 rwhp and I get to enjoy that additional horsepower for decades ahead.
And lastly, this is why we have these things...to modify and make them better. My car is never truly going to be finished. I'll do the k member and coil overs next, but after a year or so of not tinkering with it I'll get bored and will want to modify it some more.