They might be able to rig some sort of lion hood for you.
I would also maybe make the recommendation of seeing if anyone has the 'vincent' wig from beauty and the beast. Cosplay sites such as these might be a good place to go for it:
You want something shaggy, but well kept. Another way to dodge the cougar comment is probably a tail with the puff at the end of it. Once again, recommending northfur: