2 sheep in 1.5 acres is fine if they are just pets.....I am assuming you have given them a good poke under all that wool to make sure they are not skinny?
If they are breeding sheep....or will be, a different regieme will be necessary....have you got any books etc on keeping sheep? Have you been on a sheep keeping course or spent time with a shepherd? I can reccommend you find out a little more and then you can decide!
There are several ryeland breeders on this forum who I imagine will be happy to help advise but general sheep husbandry knowledge is needed.