1970 short wide. lots of questions!! help!

[CRCustoms]

finally bought my first chevy. it has come a long way from the ditch i pulled it out of (i had to cut the bushes out of the motor to get it home).

to sum it up, i have replaced:

all brake lines, shoes, cylinders, and rear drums, master cylinder

holley fuel pump (is 80 gph an upgrade?)
edelbrock 1406 4 barrell carb 650 cfm
edelbrock intake manifold
added power steering (what a pain)
new tires, headlights, fuel lines/filters, rollpan, windshield, wiper motor, stereo w amp, fiberglass door panels, heater blower/core/vent box, radiator, valve covers, breather, alternator, i could list more but thinking hurts.

im getting to the point where my knowledge is slim, and need the advice of the big boys

here are my biggest questions, in order of importance:

replaced the turn signal switch, and in doing so stripped the threads of the steering shaft (at the steering wheel) wheel is less than half way on the splines, and is holding but scares me to think about the wheel coming loose. i want to replace the entire column (despite the $50 switch) with a more modern, tilt column. i heard a 94 chevy truck column would fit? also read about aftermarket ones? truck is far from origonal so that is not a big concern. where can i get an aftermarket coulmn?

truck is a short wide with 350 5.7/3 on the floor trans. rear main/front main/oil pan/transmission to drive shaft seal all leaking (but all slow). should i replace seals or motor? compression is good, block is not origonal.

truck is now starting beautifully! but, on the highway, motor is screaming (high RPM). rearend gears are not origonal (guessing something big), and tires are 295/50, short tires. the truck will get to high speed, but at 60 mph i bet it is around 3500/4000 RPM. i would like to add a 5 speed transmission, but if there is a simpler solution to get rpm down at highway speed i would take that route. if so, what type of trans do i need (what car) must be a manual.

last, a tailgate. the pictures show a good tailgate, but doing the brake work, my sister rolled the truck off of the ramps, directly into the tounge of my trailer (thats ok, i needed her help bleeding the brakes)
stamped "chevrolet" would be nice, but not necissary. just want it to match body lines perfect. where do i go?

also, if anyone wants these parts, come get em.

-stock intake mainifold/ rockchester carb
-manual steering gearbox
-master cylinder
-chrome fuel pump (leaking)
email me if interested

cr.customs@hotmail.com