I am decent when it comes to traditional automotive things
Time frame: 3 years
budget for the drivetrain: 25k
What I want to achieve: 200 mile range, >200hp/torque
Good news, you have lots of options. You have the budget to build pretty much whatever you want as long as you're not wasteful, and the skills and timeframe to cut as many corners as you feel like.
Range:
Range depends massively on speed. 2x as fast uses 4x as much energy to go the same distance (and needs 8x as much horsepower).
Presumably you mean range at highway speeds.
I'd say 200 miles is a very long range for an EV.
Your little Porsche will use somewhere in the ballpark of 250-350 watt-hours per mile. That 90% because of it's size. Weight has nearly no impact at highway speeds.
So, 200 miles means you need 50,000-70,000 watt-hours of battery capacity. That is in the range of the smallest Tesla packs, or 2-3 of the Nissan Leaf packs.
It's around 1000 lbs of battery no matter what you do. Can you add 1000lbs of weight to your Porsche, even after you save a few pounds on having a motor instead of an engine?
It's around 3-6 cubic feet (0.2 cubic meters) of space just for the cells, not counting mounting, housing, cabling, cooling, etc. Think of a cubic foot, and pack 6 of them in somewhere (10,000 cubic inches).
Let's put that in perspective. Your wheelbase is 52 inches, your width is 60 inches. That means if you made a box, from axle to axle and the width of the entire car, the battery would be 3.3" tall. Now subtract all the area you have to use for other things and think about where those batteries go. And then probably multiply that by 2, because this isn't water you can just pour in, you're restricted to the form factors available.
It's a lot of battery for such a small car.
If you mean 200 miles of city driving, then you can cut that weight and volume at least in half. That's almost never a problem, no one does 200 miles of driving in the city a day except cabbies on a full shift. But, just for reference, there you go.
Power:
You have to think of power differently on electric than for gasoline.
If you're thinking about max speed and track use, then you can compare the two numbers equally. It takes an amount of power to push air out of the way. If you're thinking about hour-long hill climbs, you can compare the two as well.
If you're thinking about how fast you want to be able to accelerate, note that most electric motors can be overdriven 3-10x their power ratings for short term (the shorter the more you can abuse them). Gas engines take a comparatively long time to have any power available, and they generate more power the faster they're spinning (and the more fuel they're squirting) and have to accelerate towards their redline, and no farther. Electric motors have their max power available instantly, and can be comfortably overdriven for a few minutes.
Roughly speaking your motor will weigh around 200lbs, maybe a bit more.
With your budget you'll probably be using an OEM drive unit from a production vehicle, probably one of the 2 variants of the Tesla (260 or ~600 hp) or the Nissan Leaf (120 hp). They'll be mid-single digit thousands of dollars.
OEM means you can use an OEM speed controller too.
You could get the same from a big forklift motor if you want to cut out a lot of the cost (hundreds at most for a scrap motor) and swap in some time and lose regenerative breaking (a very minor improvement in city driving range, 5-20%).
...
That's the basics. Batteries, Motor, Controller. You'll need some accessories and you'll take a bunch of stuff off, but, 90% of your cost and complexity are going to be there, so, start sourcing parts and get a feeling of what you're going to spend and do, then come ask more questions.
