in a 3-2-3 format the road team has to win two on the road basically, so you really never bet any series price in the finals. You bet MLs on individual games. The basic strategy is to bet half what you would have on a series bet on game one, if the team loses then you double down on the second game, that way you have a 1.5 unit bet in total, if the team loses the first two games then you decide whether to chase them in game 6 or 7 if necessary.
Obviously the best case scenario is you win the game one ML bet then youre on a free roll or already money in the bank and stop, so even if they lose the series you cashed in that game one situation. Worst case is obviously losing two ML bets in game 1 and 2, then having the road team sweep at home and go up 3-2 (which I dont think has happened more than twice in history) then you chase them and they lose both games 6 and 7 in the series. or basically the home team wins every game in the series. Which I am not sure has ever happened in the 3-2-3 format. But I could be wrong I didnt bet NBA for years so didnt pay much attention to it.