Some added thoughts and some amplification of what Tom has said;
First consider the fact that SDPatt has 300,000 miles on his engine and has not had the heads off!
Before you consider dissassembling the engine for a rebuild please do some serious reading on the subject of engine rebuilding. A set of rod bearings, crank bearings and a set of rings is NOT an engine rebuild. You must understand that these engines are intended to perform in the 6,000 to 7,000 RPM range. In order to do this without disintegrating they MUST be balanced.
So, everything you do to these engines must be with that in mind, EVERYTHING.
So, take the advice given above and check the compression. Then inspect the engine as thouroughly as you can without removing the heads. Replacing the rod and crank bearings is acceptable, but be sure to use top quality replacement parts. Replace the front and rear crank seals and as many other seals as is necessary. I would replace the camshaft seals and all other seals that are difficult to get at when the engine is in the car.
Other components that are original, or at the specified replacement milage should also be addressed.
If you think it is necessary, then have the motor examined by a quality shop.
If you really want to do a complete rebuild, INCLUDING BALANCING, be prepared to spend $1,500 to $2,000 at a minimum. The block should be dissassembled, boiled, then cylinder bored, crank line bored, decked, and cross hatched. Then the heads need to be dissassembled, boiled, checked for warpage, planed if neccessary, CC'ed, and given a proper valve grinding with new seats and guides. All the springs have to be tested for spring compression and any change in hight.
The cam journals have to be checked for wear and any "out-of-round" and corrected as necessary. If the journals have to be corrected you will have to find oversized cams, or have bearings made by a machine shop, or find a better set of heads.
All of the above will require a top quality machine shop and a lot of shop time at $85 to $100 per hour. Remember the word BALANCE? Well in order to do this the shop will do 80% to 90% of the work by machine, and the finish work by hand, interpret TIME.
Think about what it is you want to accomplish. Are you building a race car, or do you want a dependable daily driver?
