It doesn't have to be complicated. There are 10,000 different things you can do to make the 400 run better, but what you have chosen will make a substantial difference in your car. The 6090 heads were designed for exactly your purpose and the 10230701 cam will work fine in your engine. If you chose to go to a 3.55:1 gear the whole combination will make the car feel like a rocket ship vs what it is now.

When you learn from these few changes and later want to do the stroker, sell the heads and go to a more performance oriented cylinder head.

This is a quick example of what a 400 will do with less compression, cam and airflow than you are planning.

low compression 400 on the dyno