Lifter tick

Also lifters quiet down under slight revs.

Welcome to 2CarPros. What oil pressure do you have when it is ticking? Your description sounds like replacement might be the only repair, are you sure it is a lifter? I would probably pull the rocker covers off and be sure you don't have something like a broken valve spring or loose rocker that is allowing the lifter to click due to no pre-load on it.

60lb oil pressure at idle.

Well it isn't a lack of oil pressure then. If it's a lifter tick then I hate to say it but you likely are looking at replacing them.

Okay, thank you for the helpful insight.. any tips on making the manifold removal easier? This engine is halfway into the body of the car so access is limited.. any advice is greatly appreciated.

That car is a bear to work on. I've wanted to cut the body off of a few while working on them. One thing that can help is to remove the engine mounts and let the engine set into the cradle farther. However, when was the last time the clutch was serviced, It might be easier to pull the engine, reseal the engine, maybe upgrade it a bit and install a new clutch assy. while it's out. There are cams that would give you a bit more power as well. If you're going to need to get into the engine anyway.