Maybe someone else can remember the exact temperature range that rabbits are happiest at, but if my memory is accurate you really have nothing to worry about. Far as I recall you are at the lower end but still with in the range.
I’d suggest you give yourself a little time with him, once you know about his chewing habits it will be easier to work out what is best. But its worth pointing out that they don’t view these things the same way we do, … having different kinds of flooring/surfaces for him to lie on is important (not because of temperature but because of his paws and joints), however, lots of rabbits ignore the softer options provided by their humans and Choose a plain hard surface to rest on.
Something you could get right away to help in those first few weeks are some untreated grass, straw or hay mats. That would give him something besides the floor to lie on and its fine if he eats them. Both this store (Binky Bunny) and the Busy Bunny carry a nice selection of different sized grass and hay mats, … its an easy safe solution.
You may get lucky, some rabbits can have soft things. Mine ate the cotton towel I offered (and removed), don’t eat their grass mat (that I bought for them to eat, … love how they do that sort of thing), and have two little rugs in their condo. They have carefully ripped up a large section of the fibre on one rug (they pull it off and pile it to one side not eating it so I just pick it up and let be, if they want a bald rug that’s fine by me), and the other (identical in all details except that its on a different level of the condo) hasn’t been touched.
I know cardboard boxes don’t sound lovely but they are surprisingly warm, (a grass mat in one would also be cushiony) and unless they eat an excessive amount chewing on them is safe, and a box that is destroyed won’t cause you any upset, boxes are not hard to come by.
Hope some of this may be helpful.
Looking forward to hearing about your new family member, … good luck bringing him home and settling him in.