Some good points already, torx convertors that are too tight for the cam will cause a big drop in idle rpm when trans is put in gear from park.
What are cam specs?
Recheck TDC and the timing tab marker and the damper 0 mark align when #1piston is at true TDC compression stroke, maybe you timing is way off but it looks OK with light due to misalignment of marks.
Fuel pressure 5 - 5.5 psi no more?
1405 is 600 cfm, not too big, do the idle mixture screws actually cause and effect on the idle quality/rpm? how about on the idle vacuum wg"?
When on the road how does the thing run? does it run OK other than idle issue?