If you are very good at basic wiring and can understand basic schematics for autos, the best deal going is the EZ wire kits. While they don't have all the whistles and bells, you will also have to hunt for new dash sockets which aren't very hard to find, but not a lot of $$. Check out www.ezwiring.com
Some mid-stream wiring kits are Centech Wiring, a very high quality and more complete kit. www.centechwire.com
...I highly recommend them too.
The Painless and Francis kits are much improved over the last few years even tho I have heard issues with service and help. I really have steered clear of their products over the years because of early model problems.
American Autowire/Factory Fit is the best going for "plug and play" albeit expensive!
Also on my soapbox on 30 year old wiring. CHANGE IT! The reason is that the copper can be corroded not only at the ends but also creeps up the insulation to inside the wire where you cannot see due to moisture "wicking". Moisture contamination often finds its way up the wire and corrodes inside and creates poor conduction performance. You may not even see this.
The other reason is insulation can be very poor even when pliable and looks are deceiving. Obviously if the insulation is broken and brittle there is a problem. But, I have seen what appears to be older insulation in good shape degenerate into oblivion in just a year with just the heat of summer etc. These old wiring insulations are cooked and fried with heat, UV light and moisture contamination. They are also made of inferior materials by today's standards. In my opinion, old wiring is a disaster waiting to happen. The original designed lifetime of the wiring system in the 60/70s was only 25 years according to GM specs.
And...don't think just because it was stored in a little ole ladies garage for twenty years it's any better. Active chemicals in the air such as ozone and other airborn contamination will degrade the wiring insulation sitting in the garage, in the dark!
My recommendation is just bite the bullet and change it. It's one of the best upgrades you can do to your ride.