Need help cooking ribs!

"I had planned on making baby back ribs for my anniversary tomorrow, but when I went downstairs to check, realized my husband (not an expert in these matters unfortunately) bought beef ribs and "country" pork back ribs instead. I've never actually cooked ribs before, but found an extrememly simple and highly rated recipe for baby backs on allrecipes.com. Anyway, I have gone ahead and rubbed them with a dry rub, coated them in bbq sauce and wrapped them in foil. They are now resting comfortably in the fridge for an overnight marinade. Does anyone have any tips or suggestions on the best way to cook them?? The baby back recipe said to cook them in a 300 degree oven for 2 1/2 hours and guarantees glorious results, but that is for smaller baby back ribs and these are definitely larger than that. Can I go ahead and cook them in the oven but adjust cooking time and/or temperature (presumably longer time/more or less heat)?? Any advice?? Not wanting to get sick from undercooked meat (or have to eat tough dry ribs either), especially on my wedding anniversary. I would really appreciate any help you could give me."