What's the weak link in my 440 build?

For street duty, I think I would ditch the 4speed for that combo.
Or tame the build and add NOS at the track.

The problem with a 4-gear and a big cam,
is trying to drive slow; 950rpm with 4.10s and 29s is ~7.5 mph. 800 is 6.3mph. And there is a very good chance that this will produce some serious bucking at the ~32/34* of locked out timing you might be tempted to run.
More likely, your minimum speed will be much higher. Toeing the clutch is not a good option.

With closed chamber alloys and tight-Q, you can, and to be competitive, will have to, run more cylinder pressure. But on the street,with a big cam, this quickly feeds back into the 4-speed and at "normal" timing, will produce bucking.

Bucking, if you don't know it, is what happens when, as the rpm drops, the individual power pulses are so strong, that they hammer the driveshaft mercilessly, 4 times per engine revolution; and the trans/rear gears multiply this by their combined ratios. It begins softly, and rapidly builds because the pulses are delivered to the chassis, to the floor, to your right foot, and into the gas pedal. The nose of the car will rise and fall lock-step with the pulses and resembles a bucking horse. Once it starts it does not stop by itself, you have to clutch it. This gets really annoying, so you end up with your left foot slipping the clutch, and depending on what clutch that you are running, that can get real old real fast; not to mention all the heat going into the flywheel..
So after the first session or two, your desire to drive it on the street will be much diminished.
There is no cure for bucking if you have a 4-speed, only the tempering of it. The primary method of easing it is retarded timing. This reduces the cylinder pressure by lighting the fire late and the pressure chases after the fast falling piston, thus reducing the torque into the clutch.
The second trick is reduced cylinder pressure,see above. Timing is just way cheaper and easier than new pistons.
And the third easement is a smaller cam, with less overlap and a longer power cycle..
Of course all three of these are counter to racing.

The closest to a cure, is a hi-stall TC...... which is not counter to racing,lol. Most or all of the bucking will get lost in the fluid coupling.

[email protected] is not that big a cam for a 440. I ran the Dc 292/292/108 in my 367, which measured [email protected], and that is when I ran into bucking. And that is when I purchased the dash-mounted, dial-back, timing device. Mine has a range of 15* . I used it to develop my timing curve, which ended up being 12/14 idle timing, and I set the device to be able to retard the timing to 5*. My cylinder pressure with that cam was well over 180psi. But at 5* it was driveable. But in the overall picture, as a streeter, I quickly tired of that cam and sold it to a racer who loved it.
Two cams later I was at [email protected], and a lil less pressure, and now, the DB timing device allows 500/550 rpm, and with 3.55s and 27s this makes 3.7 to 4.0mph possible for me. At 550, the engine has just enough power to pull itself on flat,level,hard ground, on the curb-idle screw, so no input from my right foot to muck it up. It can pull itself up a gentle incline but when she drops to 500, stalling is imminent,lol. I just dial in a couple more degrees of timing and up she crawls, but once over the bump, I gotta dial it back rightaway or bucking is imminent.lol.
Car has gone 93 in the Eighth, with this 230* cam, at 3457 pounds and at 930 ft, with a 60ft of 2.4 and change.
Hope this helps,lol.