If you want to use your long block then use it, you can get 275hp out of even swirl port heads. Bowl work helps a lot on those heads because that's where the choke is, if done properly they can actually work quite well, but that is a lot of time and effort to get there.
I'd stick with the TBI, bowl port the heads, run 4VR pistons and a cam with about 215/215 duration on a 108LSA 6 degrees advanced. I think Isky makes something close to that. Headers are a MUST. probably the single best thing you can do for both power and mileage. That setup, even with a stock TBI unit and intake should be good for 275hp and plenty of torque. Its basically a stock rebuild with flat top pistons, bowl work, and a cam swap.
If you have poor gas quality I may use dish pistons to keep the compression down to 9:1, BUT this will affect you low end torque and throttle response.