Hi CapitalB, welcome!
No issues removing the brake drums, the ends of the original bolts were peened as an old school way to prevent the nuts from working loose. The easiest way to remove these nuts is to use an angle grinder to grind off the peened end of the bolt down to the nut itself and then spray them with your favorite penetrating oil (I'd recommend PB Blaster) and let it soak for a couple days. If you're lucky, the nuts will loosen without too much trouble. If they're stubborn, you can try using an impact wrench or carefully use a torch to heat the nut/bolt to get it to loosen. Worst case scenario you may end up snapping some of the bolts getting them off but that's not a big deal, I would personally recommend replacing them anyways. If memory serves me correct, they're 7/16" carriage bolts. I'd recommend using grade 5, grade 8 or stainless steel replacements (available through McMaster-Carr if your local hardware store doesn't carry them) and use locknuts vs. peening the bolts when you put it back together.
Once you get that done, I'd recommend spraying the wheels down with Purple Power or your favorite degreaser, let it sit for a day or two and scrub the hell out of them using scotch brite pads. Once you've knocked of as much grease and grime as you can with that, sand and brush them until they're nice and clean.
After that, I'd recommend carefully inspecting the spokes looking for any cracks or gaps. Assuming that the overall structure of the wheel is tight and does not have any obvious structural problems, clean out any of these cracks and work a high quality water proof wood glue into these cracks. Once you've done that, hand sand the spokes until you have removed any dried glue, remaining grime, finish etc.
Now it's time to oil the hickory spokes. I highly recommend using RAW linseed oil to start with, cover the spokes with the oil until it won't absorb any more. Come back the next day and do it again, and again until the spokes will not take any more oil. The reason I recommend using raw linseed oil to start with is that it will soak deeply into the dry old hickory much better than boiled linseed oil which will polymerize limiting how deeply it can penetrate.
Once you have done all of that, wait a week and decide how you want to finish the spokes. You have three main options 1) Oil them with BOILED linseed oil (it will polymerize/dry to protect the wood and prevent them from drying out). 2) Varnish them with a high quality SPAR urethane (for use outdoors, resists UV rays and cracking) lastly you could paint them if you really want to.
When I did my wheels, I used a Spar Urethane varnish and they turned out pretty good. Below is a picture of one of my rear wheels after restoring next to a front wheel before I restored it:
![[Linked Image from i.imgur.com]](https://i.imgur.com/R6NuwUc.jpg)
And this is what they look like now after completion:
![[Linked Image from i.imgur.com]](https://i.imgur.com/tYlR6tD.jpg)
-Tyler