When the engine was rebuilt prior, do you know how much work was done on it? If they did machine work on it and bored the cylinders out, you may not have enough material left to re-bore. In which case you would need to purchase a new or reconditioned block anyway. If you have never done this type of work by your self before I would honestly take it to a shop and have them do the work. There are a lot of measurements and tolerances that need to be met to allow proper operation of the engine. If you don't correctly measure some thing or over look something the engine will never run right and has a higher potential to fail. Remanufactured engines are the most cost effective way to put new life in to an old car. If you comfortable pulling the engine, then the swap will get you running faster then doing the work your self. I rebuild engines all day long and I'll tell you, there is over 1500 dollars in just tools required for rebuilding an engine. Not to mention having to take the head and block some where to have the machine work completed on it. For a one time shot it’s not worth it to do it you’re self. Also getting a remanufactured engine gives you 30,000 or 3 years on the engine. That’s nothing to sneeze at. You don't get that if you do it your self.