Hi greg--------------Just about any 5-speed from '78 to '83 will work. Most folks prefer the combination of an '81 to '83 trans coupled with the 3.90 R-200 differential from these same years. '78 and '79 5-speed ratios are similar to the 4-speed except for top gear. '80 5-speeds are unique, and have less desireable ratios for this swap.
Roadman
Gulfport, MS