Thinking about a build for 300/350 horse.

If a 87-93 302, TFS top end kit will likely get you there.

That consists of Twisted Wedge 170cc heads, stage 1 cam, and the Street Burner intake manifold. With some other supporting mods like exhaust and the intake tract (MAF/TB) you should be there. Would probably pair the calibrated MAF with some 24lb injectors too.

From my personal experience, without a proper tune you may get some low RPM bucking with the cam.