The 274 duration at 0.050" is a little on the high side for only 10.5 CR, but with 496 CID it might be OK. However, that much duration will really like more stall speed, 4000 minimum and the more the better. That should enable 1.5x sixty foot times (2 tenths right there).

Get the cam position checked. If it is retarded, that is killing it. If it really has a 114 lobe separation angle (lobe centers), then 3 degrees retarded would put the intake lobe installed position at 117 degrees after top center (ATC). Just moving it to 108-110 ATC would help some. Maybe the guy meant 114-3= 111 ATC which is OK. This can be checked with some timing tape on the damper and a dial indicator on the pushrod. Piston to valve clearance will be changed by advancing the cam...

I think the 3.91 gear is fine even if a little more might be optimum. I estimate that tire is close to 30" dia, so a little shorter will act like more gear ratio.

Although the Victor is a great intake, the Edelbrock RPM dual plane will work great up to around 6000 rpm and improve low rpm drivability also.

My suggested order:
1) Check cam, set installed position if off
2) Swap intake, easy and not expensive
3) It really needs more converter stall speed