Put some Loctite 574 on them and tap them in.

Most are saying don't remove the studs but my thought is that they are typically hot tanked, maybe ultrasonically cleaned, and tumbled. That process removes the protective coating so now everything not getting oil will rust.

Also, Kevin, can you tell me about your surfacing process?

Tom,

I have a few pieces of old stone countertop I used as the true/flat surface. I think they're granite or quartz. Whatever. A crank-out window from my previous house is what I used before I obtained the countertops. I had the window on hand as a result of some windows being replaced under warranty for leaky seals (argon insulating gas escaped) but you could use a piece of glass from just about anything or even a mirror.

I place a couple of sheets of wet sand paper on the countertops and tape them down with HVAC foil tape which is mostly water resistant. Paint masking tape works ok too but doesn't resist water as well as the foil tape if I recall correctly. I spray the paper with water and evenly rub the parts over the paper to "machine" them. Note that the finish does not have to be a super fine/smooth finish. I first started using 1500 grit paper and it took far too long to do the job and I realized I didn't need that fine of a finish. Even 400 grit is finer than the original machining that was done to the parts when they were first manufactured. 400 grit goes MUCH faster and it's no fun rubbing the parts by hand, so you want it to go as quickly as possible.

You rub for a short while, spray some more water to keep the paper clear of the material you're removing. Occasionally wipe up the murky gray aluminum water with a clean towel. A good way to track your progress of flatness is to color the parts with a sharpie marker. As the color comes off, you see what areas are still colored and those spots are low. Note in the picture above which shows the bottom of the housing, there's some red coloring still there. I considered that "good enough" since most of the coloring left there is simply trapped in the original machine marks

Tom
I don't think these large parts are typically hot tanked, tumbled, and certainly not ultrasonically cleaned. Other than tumbling, those are things you might do with an oil cooler. Not case halves or other large parts. Lots of cost and effort, little reward. Parts washers can deal with non-sealing surfaces. Shops often have a sort of parts recirculating spray booth so no one needs to be doing it by hand. To deal with oiling passages you need to remove plugs and run brushes through, or run a lot of cleaning fluid through them, or just eyeball their insides. Or pressurize them and watch that the fluid comes out as it should and where it should.

Walt,
I think Ollie's offers these services for most parts. I know I have read posts from other builders that have these things done as well. I have no expertise.. only reading to become informed during this rebuild.

http://www.olliesmachine.com/uploads/ollies_price_list_March_2019.pdf

There are lots of things which can be done. How necessary each one is is different. An engine which blew up has rebuild needs which aren't necessarily the same as a rebuild of an engine which has run fine all its life. Doing more than the minimum is often a question of budget, too.

Some guys replace the valve cover nuts and washers every time the covers come off. Cheapskates like me just reuse these parts (its my car, not a customer's), and replace the washers only if they have been so narrowed that they have to be pried off the studs. A shop isn't apt to do that, because the cost of these parts new probably exceeds the labor for cleaning and inspecting them, and they want their engines to look good.