Engines that are set-up for hydraulic lifters have an extra oil galley drilled the full length of the engine to supply oil to them.
A engine that is drilled for supplying oil to hydraulic lifters can run either hydraulic or solid lifters. An engine that is not drilled can only run solids(although I have devised a way to use hydraulic lifters in my test engine that is not drilled).
The main issue with balancer pulley diameter is fan speed. If the fan is over speed-ed, it can lead to fan cracking/failure.
