New 4.3 won't start

I recently replaced a blown motor in my 97 blazer. We finaly got it to run after some nasty little mistakes ( not installing the crank pos. sensor wheel on the crank) it ran for two days. Once long enough to find an oil leak around the timing chain cover and then long enough to drive around the block. While driving around the block i noticed a ticking noise, like a u-joint tick. When I started the motor the next morning the ticking was in the motor and I turned off the motor checked fluids and it restarted but with hesitation. I turned it back off b/c the ticking was getting worse, and now it will not start. ?????

What kind of engine did you put in it?
New, used or rebuilt?
When it was running did you have good oil pressure?
On the ticking.
Was it in the dist cap or center or top of engine?
I would start by pulling the valve covers and checking things in there.
Rocker arms and push rods.
Also run a compression check on it.