It's a 290 degree cam, which is a hairy cam, the clue is max power at 5500, should be way higher than that, I'd expect 6500-6700 for max power, so first thing I'd do is re check the cam timing.
A 290 cam can be used with a vac advance, on some engines, but the loss/lowered of vac signal can have the advance retard mech bouncing all over the place.
The dyno op should have removed/blocked the vac pipe and tried a dizzy swing at the very least to establish if a better ignition curve would suit it better.
With the mods the engine is likely to need more initial advance lower down but LESS overall.
On x flows etc I used to set the timing so that up to around 1/3 throttle was nice, then bend the stop tabs in the dizzy to limit the advance weights being able to move out so far, to limit the total, worked perfectly, even though you wasted a day going up and down the road.
tabetha