You've already got an LS block, which means upgrading to the B20 would be a few hundred bucks and more work for just a bit of displacement. Of course, you could sell your B18B as a whole though, and reclaim some of the costs. That's up to you, do the research and see what sort of B20's are available to you.
Now, talking LS/VTEC, yes, 190-200 WHP is possible. It's a bit of a project, and it's all about doing it right if you want a motor that will actually hold together for a while. The B16 head is most popular, it's cheaper than the GS-R head, and if you throw the Type-R pistons in, you're talking about a "Baby Type-R" engine now. It would be a quick, budget N/A motor for sure if you did it right. Consider doing some more building of it. Port and polished heads, boring and sleeving, etc. All depends on how far you want to take it. Get some quotes from machine shops around.
Bolt-ons won't make a world of difference compared to the build of the motor itself, just make sure you don't buy complete crap that will fall apart and require replacement.