Once exhaust is done, then you design cam to tie it all together. Book mentioned here is highly recommended.
http://www.mezporting.com/exhaust_length.html
I recommend
Elgin Gams (original Dima, there's some copy-cats out there). I prefer him over Megacycle or Web Cams Inc (not recommended). I've gotten cams from Web Cams with 4 different lobes all rotated to wrong angles.
If you're using factory intake-cams, use factory exhaust timing and retard intake 1-1.5 degrees and go from there.
https://www.spearsenterprises.com/pr...300-2008-2017/