Motor wiring is really easy - I typically can do one like what you're doing in about 30 - 45 minutes now depending on how involved I have to get. Some of the Singers have motors that have the leads marretted to the wires that you plug in. Those are about a 20 minute job and most of that is getting organized and getting in. The ones where I have to wire right to the coils take a little longer, usually with that underwriter's knot and having it sit just so, so that nothing's rubbing on it. So, yeah, maybe put aside about 2 hours to be able to go slow and take breaks for your first time. I pretty much consider that to be routine maintenance with any machine I get nowadays. The potted motors are more work because of the worm gear and the extra cleaning involved there, so an external belted motor is a great one to start on. My first motor was a potted motor and it was right about the time Rain put his tutorial up, so at least I wasn't going in blind.
You're lucky with the spool pin in that it's on a cover and you can take it and brace it and drill it. The bolts that suck are the ones that are attached directly to the main part of the machine then you're wrestling the weight and bulk of the machine.
It's not about strength, it's about steady. I drilled a really stubborn bolt out of my dirtbike from the back but I can't recall if it was with an easy out from the back or a regular bit from the back. Maybe someone here who's not so directionally challenged can chime in? I think it was something like I was drilling a pilot hole from the back to use the easy out and it spun out the front with the drill bit? The hardest part here is going to be having a drill bit small enough to not ruin the threads or you'll have to chase them with a tap and hope there's enough material left.