Seems reasonable.. Call Game 1 a pick'em with an implied 50% chance of winning. 5Dimes now offering Giants for the series at -190, a 65.5% implied chance of winning (including vig). Multiplying those odds gets you to a 32.75% figure, which would make the line +205 (1-0.3275= 0.6725... 0.6725/0.3275= 2.05). Throw in some extra vig for the prop bet and there ya go.. +175 seems dead on and incredibly reasonable.
Nice game 1 win. Good luck with the series, MoneyMiller!