Likely more negative camber is needed and quite probably too banzai with corner entry speed and/or not using the brake to get weight on the the front tires for better bite.
Technique is important too.
A lot of good info, such as this, flowing through here. Good call, BULLITT1992, on the CG lock. I almost missed the comment about seating/driving/bracing issue.
My first thoughts were, what tire pressures were you running and alignment settings? Sometimes, tire pressures may affect u/s. A small camber change, from -1.3 to -1.9, did wonders in the understeer department, on my Cobra.
Some of the information is based on years of suspension tech in this sport applied to this platform. While the suggestions may seem minor compared to your list, such as a good
alignment, they are targeted to reduce/cure your biggest problem...understeer. There are many good vendors to choose from for your parts. IMHO, you may want to consider having real world tech vs salespeople to help you fix this possible scenario: You throw a mess of name brand parts at the car with high expectations, and the results are as bad or worse than before. Ask me how I know.
Keep it simple, learn
to drive faster, and stay on those tires until the suspension/chassis is fully
sorted. None of this is new or ground breaking information. It's all been said here before, in one way, shape or form. Just my 2 cents.
Good luck and have fun with it,