With the fridge at 43°F, the fermentation temp will be easily 51°F. (Fermentation generates heat.) So you're good. You can reduce diacetyl (not a big problem with 34/70), and just speed up fermentation, by raising the temperature at the later stages. If you can't control temp, you can just wait until you are at or under 50% of OG, and just move the fermenter to a cool room temperature, like a basement. All the temperature-sensitive flavor producing effects happen earlier in fermentation, this won't make it taste ale-like, just clean it up and finish it off faster.