wood is cheaper and better than plastic. Also more secure.
However plastic doors are very profitable, which is why so many companies are keen to sell you one.
I prefer hardwood, and treat it all over with Cuprinol clear, plus paint those parts of the frame that you will not be able to reach afterwards, before fitting. But a lazy cheapskate will not bother.
Get a competent local joiner to fit it for you. You will probably need a new frame as well, and this is usually more economical than fannying about trying to repair and plane an old one. At 140 years old your old frame is probably rotten, warped, riddled with holes for old locks and bolts, encased in cracked old paint, a non-standard size, and fitted with rusty hinges in screws that won't come out. Allow for 3 new hinges, preferably stainless, mortice rackbolts top and bottom plus a mortice deadlock or sashlock. He will fit them in very little time if done when the door is going in, faster and neater than most DIYers could manage. If you buy the parts yourself they will not cost much, but make sure he is not expecting to supply the lock at retail prices as he might have calculated this as part of his profit margin.
