All the factory motors are reliable stock if you keep them at a reasonable rpm and don't over carburate them.
The blocks are the hardest parts to find,as they are the first items detonated by broken pistons,rods,crankshafts,and other internal parts.
I intend to try to keep my current motors as long as possible,and keep them at a relatively low rpm.
One of the reasons torque is so important.
Most complete crate motors I've seen run about $6000+,for big displacement.
Some chevy small blocks can be had starting around $2000.