I've found that bulking up on power in a HR park is the best way to get to the postseason. For me, that usually means grabbing up the sub-$4 mil, non-* starters with minimal BPHR.
Wegner is a favorite for this approach, as are Nagy and Washburn. Torrez can be adequate, if you're looking very cheap. At the high end, Moose or Chance. You also need a fairly deep but affordable pen with this approach. Guys like McGinn, Humphreys, Sembera up top, with Linzy/Lopez types behind them. If you've gone cheap with the starters, and miss out on a couple of the big sluggers, you might be able to afford a top tier reliever, like Tatum, Perranoski or Wilhelm. Tatum, esp., can do a lotta good in this set up.
But you can definitely build a winning team in '69 on a number of totally different models, despite the small player pool. Which is one of the best things about it.