Hi, I am trying to find the best hydraulic lifter available for a 66-67 Olds 400 engine.My friend had major oil pressure problems because of bad lifters.They took apart an old lifter and compared it to the new lifter and it was something with the metering disc in the lifter.They were able to locate a set of old stock Johnson made lifters and that did the trick.Are there any good sources for new lifters that actually work?Thanks,Tim