LD340 Can’t Get The Carb Base To Seal

Ok I get it now, I think.lol

To the OP
Ok so, to clarify; When you run the pcv to one runner like that, it wreaks havoc on the AFR in the cylinder that you have plumbed it to. At idle, it will probably misfire and leave you with a dead cylinder. That PCV HAS to be plumbed to the front port which exits under the primary throttle valves. Here it mixes with the transfer/pilot fuel, and you can twiddle the mixture screws to compensate for it.
Furthermore, at idle, the engine needs a certain amount of fuel, that has to be supplied by BOTH the transfer slots AND the mixture screws together.
If your transfers are not supplying enough fuel, then,the mixture screws will have to make up the difference. This is fine at idle. But then when you barely touch the gas pedal, the throttles open up and because the mixture screws are dialed rich, the engine goes rich; and while not ideal for cruising, at least you don't get a tip-in sag.
If your transfers are supplying too much fuel, the the mixture screws will have to be adjusted lean in compensation. This too is fine at idle.But then when you barely step on the gas,the throttles open up, and because the mixture screws are lean, the engine gets a lil sag, a flat spot, or an outright hesitation. Plus, at cruising speed she will be a lil lean, and if the entire circuit is lean, it can overheat your plugs and cause other driveability issues.

If you want to see what I mean,
do this; Put the throttle upon the fast idle cam at around 1600 to 1800 rpm, and let it settle down for a bit. Now, shut off the mixture fuel, by screwing in the the screws all the way. Notice how the rpm took a hit. now, screw the mixture screws out, until the rpm rises to a peak, then close them 1/4 turn. At whatever rpm the engine is turning, it now has the correct amount of fuel for Neutral/Park. No load running. This will also be very close to ideal in second gear at that running rpm.
Ok now flip the throttle off the fast-idle cam, and see if it will still idle at this mixture-screw to transfer-slot ratio. Do not change the mixture screw setting! If the engine doesn't like this setting, change the transfer fuel instead, by cranking around on the curb-idle screw. If the idle-rpm is unsatisfactory, change it with more or less timing. Voila.
You now have the low-speed circuit tuned for best lean torque at whatever rpm it settled in at.And you also have the idle mixture tuned pretty close. And check out your idle tip-in, It too should be sag-free.
If you changed your Idle-timing, then you will have to re-visit your Power-Timing, and limit it to 34/36*.. END.
As to the brake booster line; I don't like running it to just one intake runner. Every time you step on the brake, the engine will make a little shudder, as the diaphragm readjusts inside the booster. Instead, if the carb has a spigot on the back for that, I use it., If no spigot, I drill and tap the plenum on the secondary side, and install a spigot there.
The port in the intake that you used, to plumb the PCV, is better saved for plumbing to other devices, like a vacuum amplifier , HVAC controls, or emissions devices.
As to air leaks around the throttle shafts; On a V8, the only time I would pay attention to it, is if the throttles do not sit the same on the transfers. Otherwise, it is just a part of the Idle-Air bypass.

Whoever it was that said to check your choke; he is of course referring to the fast idle cam. I neatly avoided that scenario by advising to be sure ALL four throttle valves were closed. I'd credit him, but I cannot find the post?

Thanks for the info, this helps.