The cheapest, simplest, decent ignition is to use an early 2.6 / 2.8 distributor with vacuum and / or centrifugal advance and a suitable coil and a Pertronix electronic ignition kit to replace the points.
The cheapest, simplest, upgraded ignition is to use a 2.8 Duraspark distributor and control unit (amplifier) to replace the ECU and TFI / EEC-IV distributor ignition.
The best (in my opinion, without restoring to fabricating parts) option on a carb'd truck is to use an upgraded Performance Distributors 2.8 Duraspark unit and an MSD box to replace the stock Duraspark control unit. Of course this is also one of the more expensive options. The distributor is around $300 and the MSD box around $300, plus coil.
According to the FAQ's / Tech Articles there are cams available from CamCraft (never heard of them), Crane (through Jeg's / Summit), and Racer Walsh. The Racer Walsh info is as follows:
2.6/2.8 V6 cams
Stage 1 cam gives a smooth idle and low and mid range power boost without sacrificing economy. Stage 2 cam is a street/competition grind. Higher lift and increased overlap give a rougher idle. Good midrange power increase. Specify engine year when ordering: '72-'83 had smaller cam journal size than later years.
6411 STAGE 1 CAM (260 DUR 425" LIFT)
6412 STAGE 2 CAM (264 DUR 448" LIFT)
6477 VALVE SPRING SET 2.6/2.8 V6
6449 RETAINER SET STEEL
6489 PUSHROD SET (STOCK REPLACEMENT)
6487 LIFTER SET (STOCK REPLACEMENT)
Let me know if you have any questions! There are also intake manifolds and carburetor options, header options, etc... but beware they can be pricey.