Looking for more pep off the line
Holley 600 cfm vacuum secondaries, TCI 141500 converter, 3.23 rear gears, timing set at 12-15 degrees BTC
This indicates that it hasn't been tuned.
So that is your next step now that the build is complete.
A hot rod can not be set to specifications worked out by the factory because by defination the hot rodded engine is unique.
You can use the factory info, etc as a baseline, but to adjust the timing and fueling requires making changes, one at a time, and then testing for improvement.
The best way to tune is begin at the lowest rpm (idle) to develop the most torque. Make a small change to timing, adjust fuel mix if and test for power in gear (least change of rpm engaging drive if an automatic). The reason for starting with idle rather than wide open throttle or high rpm cruise is that both timing and carburetion at higher rpms/wider throttle openings build on the low rpm/ closed throttle settings.
Before getting too far along in the process of tuning there are two things you must measure.
1. Closed throttle position relative to the transfer slots. (see post below)
2. Timing versus rpm from as slow as it will go to as fast as you are comfortable. (
example here)