305K Maintenance Questions

My beloved '95 Sport 2dr has recently hit it's 3rd century and I have started to have my first internal engine issue, low oil pressure. I've decided to rebuild the original oil pump in the 4.0 versus purchasing a new one, as it's a $30 dollar savings. I'm planning on plastigaging the main and rod journals and r.r.ing the RMS while I have the pan off. That said, I have a couple of other questions about what all else I may need to do at this time.

I've got a few other concerns/issues that may need to be addressed and I figured that I would ask the experts about helping me come up with a plan of attack.

First, I'm getting some blue smoke at long idle intervals. Like if the engine idles for 5 minutes or more. I'm pretty sure that this is just valve stem seals as compression is still good as is power. My question is, what all else should I replace while I have the valve cover off? My last stop at my local machine shop, I spoke with the machinist about how much a 4.0 HO head service would cost. He told me that almost all the 4.0's that he works on need guides, especially the exhaust guides, and either new valve springs or shims as the factory springs lose pressure, in his words, quickly. So, have any of you guys (and gals) heard anything along those lines before?

Also, I have the very last exhaust manifold bolt broke off in the head. I don't know how it happened, just started noticing the tick-tick-tick getting worse and worse at start up. I guessed it was either a manifold weld crack or loose donut gasket, but after tracing the sound it was what I first thought was just a missing bolt, but it turned up to be broke off just under flush in the head. I have no idea how this happened, but has anyone ever been able to get a drill and easy out in to this location? Looks damn near impossible and I really don't want to pull the head.

Thanks for the coming advice!

that is a common bolt to break on the exhaust manifold. and it is possible to get the piece out but i was replacing the manifold so i had no real obstructions. i still had to cut down an 1/8 in drill bit so i could get my drill in there (a 90 degree drill would have been a lot easier to work with) but it worked .the easy out worked great from there . the studs are not very tight from the factory i think 14 ft lbs so it should come right out. and if your going that far if you haven't done so already you might as well replace the manifold because its probably cracked too.

do compression and leakdown tests to see your numbers, the first cylinder is probably shot