Chevrolet: ENGINE, best bet, possiblities

Question
Well you know I've been working on cars for awhile and I've replaced many engines. I have also turned a vehilce over for a long time and this has never happened. It seems like it would have to be more then some gas sitting atop the piston and leaking down. Do you really think this is the best bet?
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Followup To
Question -
I just bought an engine a 350 long block. I finished putting the engine together. I installed it. I tried starting it and it wouldn't I figured it was out of time. I was tired thought I'd finish the next day. I came home to my block leaking gasoline. I checked my oil and there is gas in my oil. Could you give me a list of possiblities? Thank you. I really just need to know if the engine was probably put together wrong say the rings. Or could it have been something I did. Could it be the intake? The intake worked fine on the engine I took it off of.
Answer -
Duane;
  First get the gas out of the oil / change it. than  I bet that the distributor is in wrong. if the engine was built by a good place than it should be just fine. you must pop the no#1 plug to get the motor to  line up to TDC than you drop the dist in on the no#1 plug spot on the dist. cap than snug it down a lil so it cant pop up or out. than check all plug wires so all are right than it should start, if the dist. is in wrong you will never get it going. as far as your gas it must be getting flooded. so check all wires and the dist. ok I hope you torqued the heads w/ new gaskets, etc. and the intake also.  are the plugs good. again I bet it is the dist.

Answer
Duane;
  If you have a lot of gas , you can check the fuel pump to see if it could be leaking on the inside of the engine . and if the intake is for the engine it should be fine as long as it is not cracked any place. do you get spark to the plugs when you try to start it ?