340 dyno chart thoughts

What's the initial timing? That has the biggest effect on idle vacuum. If it's not in the 20* range, it's not close to correct for a 340 with that camshaft. Cam is a bunch bigger than a stock 340 cam and should make better power EVERYWHERE in that pull range to the stocker camshaft. No way should the TQ peak be below 3500 with that camshaft!

Total timing approach is a HORRIBLE method to time an engine going in a street car. Race cars too unless they are locked out!

Bad idle set ups lead to stacking issues elsewhere in the fuel curve. That thing goes fatter and loses power which is probably a fuel system issue.