It is perfectly safe to turbocharge a completely stock b18c1. As long as the engine is healthy, you can safely produce near 300 hp, to the wheels. If your end power goal is near 400 whp, then I would see the need to rebuild with forged internals. I agree with your logic to an extent, I have a built block and still buying my turbo setup. However, My power goal is 400+.

How many miles are on the car? Personally, I would invest that 1k into a turbo setup. Make sure the first thing you buy is your tunning solution. A good budget setup is any OBD1 ecu, have it socketed, get a conversion harness, and find a tuner confident with crome. You will probably need a few hundred more to complete your setup, but it sounds like you need to do a bit more research before you start getting dirty anyway.

300 Whp can be had for < $1400, do a search for "food2000" and look at what he spent.