Need advice for a 1987 Honda accord

Hi, I own a 1987 Honda Accord, Automatic 4 door. The car is in decent condition and I do wish to keep it for my next generation. This car was passed down from my dad and I wish to pass this on to my son in the future. I am currently resorting the interior(Which is rather cheap for me to do) but need a new engine. The current one works alright, but there are some issues with the transmission and a few other small parts. I was wondering if there is another engine I could swap it with. I do not have any other information on the car at this time but I could gather it if need be. I like this car because its nice and small, easy to park and has been well kept. It would be a shame to see it go to waist and be recycled. I have had this car looked at by a dealer and he said he would take it for under $500 because he felt nobody would ever want it(Understandable). Most everything else works fine. There are minor electrical issues inside such as broken lights and what not but I am a computer tech and would have no issue getting these resolved. Is there a specific type of engine I must use? Or would I have to modify were the engine sits to accommodate room for the engine to lay. I do not know a lot about cars and I do understand this sounds rather odd that I wish to restore this car. And help would be greatly appreciated and I again can gather any needed information. The type of engine I am looking for is simple. I'd like something not sporty, and something fuel efficient, were as 25+ will do. If you could please include the following in your response:
1) Is there another engine type I can use?
2) Were might I go about purchasing one
3) Would I have to modify anything to accommodate for the new engine?
4) And would there be any electrical changes that I must make

Thank you for your time as it is greatly appreciated