I've set up a page for the original Official Baseball Directions that came with the game. It's a 16-page pamphlet which goes over the procedures for a regular two-player game, discusses situations such as stealing and putting in a relief pitcher, decodes the abbreviations for advancing runners on the back of the Player Card, while also promoting a variation of the game called the Manager's All-Star Game (I never tried it; didn't seem that interesting).
If you skim the directions, you'll get a feel for how the game would have been played by two people back in 1969. The goal here would be to follow the directions and rules as closely as possible in the online version, while also taking advantage of the computer's ability to make things happen quickly, more efficiently, or to move forward in the game in an automatic fashion.
For example, kids that would play this game in the '70s would often tire of using the dials to control balls and strikes, and would immediately roll the dice to get right to the action on the back of the player card. Of course, the disadvantage of this would be 9-inning games with football-like scores such as 35-28. Without the possibility of a strikeout, batting averages (already skewed high with only 11 possible outcomes on the player card) went way up.
With the online version, it could be possible to allow the computer to simulate the balls/strikes aspect of the game whenever the player wants, leading directly to the throw of the dice if a walk or strikeout is not recorded. For that matter, the player should be able to move forward batter-by-batter, half-inning by half-inning, or inning-by-inning, if they want, letting the computer do the work.