Send it to these guys and they will rebuild it. Long block ( complete engine minus covers and accessories) is what you would want. They have my short block there right now. I have dealt with this place multiple times and never had an issue. They have been in business since 43, a BBB member since 57 and a A+ rating.
Remanufactured Engines by City Motor Supply - Domestic and Import
The very 1st engine is what you need, as of last week, they did not have one in stock, but would rebuild yours with a 2 week turnaround. If they rebuild yours, there is no core charge.
By the time you factor in parts, cleaning stuff, and machine work, you'll be hard pressed to build one yourself for this price. I have built many engines, but by the time it is all said and done, I would save about 50 bucks doing it myself. My time is worth more than 50 bucks.