It all depends on what you want your truck to do and how much you want to spend. I'll figure you just want to stay somewhat stock and have a modest budget.
1st. you (if it's a '79) have a external balanced motor and probably running a 8 to 1 compression ratio with D3VE heads which if I'm not misstaken is about 210 horsepower from the books I've read.
So we'll look at the heads first, there are several heads out there. The stock usage D3VE heads with alittle work like grinding out the thermactor bumps and alittle clean up will work fine. If you want more flow you'll need to find a pair of D2OE (PC heads) or a set of D0OE or D0VE (CJ/ SCJ heads), although your waisting money if your staying close to stock, they can get pricey. Have the head shop replace the vavle guides with new ones (don't have them knurled) and install postive valve seals on intake and exhaust.
If you are considering a larger than stock camshaft, the D3VE heads will need to be retro fitted with a kit that Crane makes to make the rockers adjustable or have the pedistal mounts machined. The others have screw in studs and pushrod guide plates.
As far as a manifold choice the 2166 will help meet emision standards and give you good torque were the 3766 is for higher horsepower in the higher rpm range.
The carb choice of a 750 is larger than one needs for a stock or close to stock operation, a 650 would do fine.
Do'nt scrimp on the headers and exhaust system, get the exhaust out the best you can, I'd suggest a minimum of a duel 2 1/2" ID. system. The crossover helps equalize the back pressures from bank to bank, a good idea.
Mandatory items are a pre '69 timing set putting the cam at straight up position instead of the retarded position it's in to meet emission standards and a MSD or alike ignition because most of your driving/crusing is under 3,000 rpm.
The biggest thing you could do is raise the compression ratio to 9.5 to 1 and still run 87 octane gas, I'm at 10.5 and still run 87 without detination.
How much do you want to spend?
Ford's don't have a posi (chevy's do), Ford's have limited slip, check these guys out.
http://www.drivetrain.com/index.html
Hope this helps.