70 ambient is pushing the limit for most non-belgian yeasts (fermentation will raise the temp 5-8 degrees during high krausen). You might consider finding a way to drop the temp a few degrees, like draping a wet towel over the carboy, putting it in a water tub and putting some frozen soda bottles in, finding a cool erspot in your place etc...). You just need to worry about the temp for the first 4-5 days, after that it can climb up and not be an issue.
That said, this beer should have enough going on to cover up any minor fermentation sins. Good luck.