Low Budget Project Suggestions and Questions?

[LACROMER]

So i recently picked up a 1983 K10 with a 5.7L 350 and TH350 transmission. I've done quite a bit of work to it so far (List Below); But i still have a lot more work to go. Eventually this is going to be a show quality truck but right now I'm building it on a budget. I am pretty good with trucks but i admit i don't know everything. So i do have a few questions:

What is the easiest way to tell what gear ratio i have in my front and rear diff?

Is a TH350 transmission going to adequate for eventually a high performance SBC 350? What would be a better transmission?

What else can i do to see a noticeable difference in power and/or ride without breaking the bank? (Engine is slowww!) (View list below before recommending parts)


Parts i've put into the truck:
Power steering gearbox
Hood latch assembly
Fan Shroud
Fuel filter
Holley Blue Electric Fuel pump (Currently pushing 5 psi)
Holley Fuel Pressure Regulator with Gauge
Fuel Lines
Edelbrock Air Filter Housing
Edelbrock Upper Intake Manifold
Edelbrock 4-Barrel Carburetor (600 CFM)
Catayltic Converter (2)
Shorty Performance Plugs (8/23/2015)
Diff fluid change (80W-90) (8/23/2015)
Oil & filter change (10W-30) (8/23/2015)
Fuel system clean (8/23/2015)
A/C Blower motor
A/C Blower fan
A/C Drive Belt
Dome light kit
Coolant overflow reservoir
Windshield washer reservoir
MSD Distributer
Duralast gold Ignition Wires
Ultima Select Starter
Thermostat
Upper radiator hose
Radiator Cap
Trans fluid & filter change (10/06/2015)
Throttle return spring
Energy Suspension Polyurethane Performance Body and Cab mounts
Sylvian Performance Headlamps
Temperature Control Assembly
Fuel Tank
Fuel Tank Straps
Anti-Squeak Fuel Tank Pads
Sending Unit

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Engine bay when I first bought it

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Engine bay now

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[Stepside Billy]

Check for a tag on the diffs. Or check the glove box. You can also jack up a wheel and count the revolutions: turn the wheel one revolution and count how many times the driveshaft turns. You can pull the cover and count the gear teeth.