Weird noise after 4 speed install

What cam are you running? 268/276/110 Voodoo703
Are you running Solid lifters? nope.
What's the idle speed? 800
the Idle-timing? 18*
the Setting of the Idle-mixture screws? fi-tech EFI
Have you set the T-slot sync? is none
OOps some of that is in Post 47

IMO
because she sounds to be idling pretty fast, with a lot of timing, most likely the T-slot to mixture screw relationship is out of whack and the engine is just struggling with AFR. Make sure your secondaries are closed up tight but not sticking.
Furthermore, at 18* timing, your engine is making too much idle-power, and the power-pulses are hammering the driveline.

I had your exact combo a few years ago, except with a Hughes cam, and 11.3Scr. I idled it at 14* in the distributor and 650/700 rpm in Neutral, with no bypass air. My T-slot exposure was square.
To reduce the power for parading, I reset the idle-timing to 5*.
That cam would idle at 500/550 in low gear@ 5* advance, pulling itself all around the parking lot, with no help from my big right foot, nor the left one. With 3.55s, that was 4.25 mph with the standard 2.66 low, and with the 3.09, it was 3.6mph
I ran the cooling system at 207*F

But I just gotta say, man that sounds like a lotta valve-train noise.Mine was quiet as can be.