Do you have any distributor now?
If not this would be your shopping list...
Stock Mopar electronic distributor $45 Advanced Auto
Yellow round Accell coil $33 Advanced Auto / Summit
Coil bracket MSD stock style $7 Summit
Borg Warner HEI 4-pin module (order for a 78 Chevy truck) $28 Advanced auto
Design 2 Drive HEI bracket $25 (optional but very nice)
I would also go the the junk yard and cut some factory connectors for the distributor so you do not have to cut any wires in your original harness.