How do you mean modern/reliable? Your truck has front coil springs and rear leaf springs, a design still used in trucks today. In addition your brakes are front disc/rear drum which again are still used on most brand new trucks today. That being said there are things you can do to help, if you would like. I would do this:
SUSPENSION
Replace all 4 shocks
Rebuild steering system including sway bar bushings, links etc
Replace rear bushings
BRAKES
Replace front rotors/calipers/pads
Rebuild rear drums
Replace all brake hoses
Flush brake system
This is the kind of stuff you can do to "modernize" your suspension/brakes. Everything above could be done very cheaply and easily with minimal work/tools. Now if you are looking for a lowered truck, 4-wheel disc, or independent rear suspension, then there are kits out there, but that is all over-the-top massive $$$ stuff that really is not necessary if all you want is reliability. Let us know some specifics on what you are looking for, we might be able to give a better answer than that.
-d
