1983 Chevy Project

[Texas1983]

Alright, so this is a project my Dad and I have been working on for 5 years on and off now (you know how it goes). It's a 1983 SWB Chevrolet Pickup that started out brown with an inline 6 and saginaw 3 speed on the column.
It's current status is a sb 350, 2 bolt main, scat crank, vortec heads w/ a three angled machine job, comp cam, edelbrock performer intake, 600 cfm holley, aftermarket 1 5/8in headers just to name a few. Basically, we took a fuel injected vortec 350 out of a 1996 silverado and equipped it with a carb. We also put a four speed saginaw that I bought off ebay in the drivetrain (now shifts from the floor).
I know the input shaft will indicate exactly what gears you have, but I didn't know that until after the fact. What I do know is that it has the low granny gear.
In addition, I found some useful information online that pretty much tells me that this truck has a lsd and 2.73:1 ratio in the rear end. I can't know for sure until my dad hauls the truck up to where i'm currently stationed.
All the body work was done by myself... that should account for the lack of attention to detail haha. It was a learning experience, and now I know to leave that kind of work to the professionals. Regardless, the paint doesn't look horrific. It's a metallica grey that I plan on maybe having wet sanded and clear coated by a body shop for the time being. For now, I just want it to look ok so I can drive and enjoy it.
Because the truck is still down in Texas I can't take new pictures, but I do have some to post and i'll have my dad take/send some more.
My next two big steps I want to undertake are getting the stance right (drop, wheels, tires), and putting a better gear in the rear end. This is where I want some input from you guys, because I know these are two very common upgrades on these trucks.
For the drop i'm thinking either 3/4 or 5/7, but my main concern is handling so i'm looking for the best option in those respects. My wheel selection is down to a few choices, but idk if I want 20's all around or 18's up front with 20's in the back. Tires are probably going to be 295/45 out back and 245/45 up front.
That mean's, i'm guessing roughly around 350hp at the flywheel, and I want to stick with a manual transmission and upgrade to a better 4 speed or 5 speed with OD later. Also, with the 20's and tire size out back I think that's around a 30in diameter. With all that in mind, what's a good rear end gear size? I want to really feel some torque when i'm playing around on the streets, but i'll never race it, obviously. It'll probably almost never tow anything, and of course I want to be able to drive it on the highway without blowing all my money on gas. I was thinking 3.42?
Anyways, enough rambling. I love these trucks and I can't wait to see this project progress. There is some awesome information on here, and I look forward to getting some feedback. More pictures soon to come as well.

[Texasupton1]

Im in Dallas and I am working on an 83 step side. Keep your eyes open in Huntsville for me an old school roll bar for the bed. My folks are just across the lake in Livinston