I guess I'm not clear about the benefit of a shift kit vs a valve body vs a tune that all change the shift firmness and timing.
Besides shift feel, I'm also concerned about it feeling mushy while accelerating in a gear. I dont want the engine to run up to 2000 and the speed catch up slowly. This would drive me nuts honestly and its my biggest concern about switching to an auto.
there are quite a few factors that come into creating the issues you're referring to with the automatic transmission.
The valve body is made of 2 separate units the accumulator body and the main valve body (actually this is made of 2 pieces that bold vertically also) The accumulator body's primary function relates to shifting. The main valve body's purpose is regulate pressures on the clutch packs in the transmission and direct fluid flow to the proper clutch pack to ensure proper operation.
If the transmission still has factory pieces in it you're not going to be happy with the feel until you rebuild it. the frictions used from the factory with mild tunes are not quite strong enough to hold the torque from the PSD even with a mild chip the additional pressures added with the tugger kit and increased line pressure on your chip help but the problem is still there when used under a load. (second thought make sure your stand alone controller will allow line pressure increases)
Now on to torque converters, you will not get the converter lockup clutch to engage below 35-37 mph these are the speeds that you're going to hate coming from a manual transmission there is tons of mush but it's the nature of the beast. When the converter locks up and has proper oil flow that portion will be exactly like a fully engaged clutch in a manual transmission rig. Though too much power can distort the converter housing enough to impact the alignment of the friction surfaces which is why you go for at lest a billet faced converter. Racer X's X6TC fits the bill nicely for your mods and gives you some room for mild injectors/turbo upgrades in the future without a new converter. The $460 converter is better but roughly comparable to what you'd buy in a parts store that they would label as "heavy duty" as opposed to the standard OE replacement; only minor tweaks but effectively an OE unit which is great for someone leaving the truck stock and willing to accept some converter slip under heavy loads.
If your budget allows now I'd highly recommend rebuilding the transmission yourself before you install it. Based on some of the options that you've considered thus far and this project it is within your mechanical abilities. I truly think that this will be the only way that you're happy with your final product with the auto. doing it yourself will save you roughly 1500-2k or at least it did for me. Call Racer X and tell him you want a quote on all the parts you need & tell him what you want out of the transmission. I can loan you the trans specific tools except the pump puller adapters since I've misplaced mine, you'll need a couple slide hammers and a good selection of bearing drivers.