I can definitely understand wanting to learn a skill and build it yourself. This is a great reason to take on a conversion project.
As far as your range goals, I don't think they're achievable in a conversion. If a 300+ mile EV could be build inexpensively, all the major automakers would do it. Teslas and other production EVs have the car designed around holding a large integrated battery pack. Your Corolla was designed to hold an engine, fuel system, exhaust, etc. and even with creative packing using those spaces your car will hold less than most Teslas. In addition, though it's a reasonably aerodynamic car, the Corolla has more drag than an equivalent Tesla, so to match range you would need more of a battery pack than a Tesla.
Buying that many battery modules (or complete pack, or whatever) will be very expensive, and that hasn't taken into account any other part of the conversion (motor, controller, charger, and on and on).
Also am I right assuming this is not your only transportation? As I said above, these conversions can take a long time (and usually a lot longer than planned).
I'm not trying to discourage you, only that you're perhaps overly optimistic with the expected result. I would look at a bunch of car conversions on this site to see what you're in for. Doesn't have to be a Corolla build as any small or midsize car will face a lot of the same challenges.
Read up on theory and price out components. Lots of people these days are taking parts from crashed production EVs and adapting them for their projects, though the price of the wrecks have gone up accordingly.
P.S. the Haynes manual can help with disassembly and servicing. As you go along you may find they breeze over parts that give you trouble, but generally I like their manuals.
