My recommendation is to ALWAYS have a beater when you have a project car or a car that takes on projects in general.
I've had a lot of luck running turbo engines with 200k+ miles, but they were relatively tame. I wouldn't consider 400ish HP tamed. At least not coming from a GE. Just save and spend 5K at once for a proper na-t build instead of piecing it little by little and you have issues all over the place.
Turbos can be reliable, but only if you spend the time and money doing it right the first time. I've driven my old 1jz cross country and only had one issue which was a bad alternator wire. ONE...thats with a single and 272 bc cams + supporting mods.
On the other hand when I was a dumb 18 year old I had a 92' Supra Turbo with 230k miles. It drove beautifully until i started modding it more and not doing things right the first time. Mark my words, you will have issues if you do not spend your resources correctly the first time. It'll give you a lot of problems and then you'll be losing money left and right, you'll realize you could've had something better by now and then you sell all your shit and a project car. I bet you 75% of projects end up that way for people your age. Best of luck and enjoy learning from the experience!