If you have a good engine builder nearby,befriend him,and ask questions. Don't make a nuisance of yourself though.
I built a 400hp 351 cleveland that was still running sweetly after 150000k.I spent a lot of money getting all the right bits,took heaps of time building it,checking clearances as I went.Spent around 100 hours on the heads,and the only thing that I didn't do,was fit the rings to the pistons.
Get the right advice,get the machining done by a reputable engine recoditioner,buy good quality parts and take your time,whilst paying attention to detail and you should have a good reliable,strong engine.

Sterling,
1st eng rebuild is good fun, there are a couple of rules, Cleanliness is God, make sure you mark everything (rod to rod cap etc), most of all dont rush, be organised, everything laid out neat before you start,slow and steady, and as someone else said good quality tools, get your torque wrench cal checked, cheap insurance, undertorque something (flywheel, rod bolts etc)and things come apart very quickly.
most of all, if in doubt stop and ask questions