There has been a couple of threads on H-T of LS's pushing 200+ whp, but all of them were running 84+mm bores, 12+ cr compression, and things like Crower 405a cams, etc etc. and LOTS of tuning.

If you can settle for around 165-170whp, it is doable on a budget. Think B16 pistons - if a B18, not B20 - crower 404's, and ST valvesprings/retainers. You can reuse your stock rods w/o resizing on b16 pistons and the rest drops in.

Also, like everyone stated, get a b16 tranny + LS 5th. You will be loving it after that.

LS's can make power, but it costs.