You can do that Chevy High Performance magazine did an article several years ago where they took the Goodwrench and went through a long series of dyno tests where they started stock then went through a series of tests replacing the GM intake and Q-jet with an Edlebrock Performer RPM and 750 Holley. Then stepped up the heads with stock but ported, L99/ZZx out of the box and ported, Vortec out of the box and ported, AFRs I think as well. This thing grew from stock out of the crate at 230 hp or so to about 410 with the stock bottom end. Of course a couple handfuls of dyno pulls isn't the same as honking down the street for a hundred thousand miles but it shows a 400 horse engine can be done on the Goodwrench foundation.
My biggest issue with the Goodwrench as the basis of what is approaching the level of an upper end high performance engine is the piston crown configuration. GM, who isnít alone in this, uses those circular dished pistons to control overall compression. These things essentially cheat the engine of a considerable amount of squish/quench by reducing the flat surface of the piston that opposes the squish/quench step of the combustion chamber because the stepped down portion of the crown is too far from the head to be as effective as one would hope for. While not the end of the known universe, it does increase the engineís octane requirement by 4 or 5 points so you can't run as much compression ratio or spark advance as would maximize fuel efficiency and power development. Still, like I said, CHP got over 400 horses from the thing with better heads and cam, and a bunch of what's considered bolt on stuff like an almost racer intake, big ol' Holley and headers. This happened under 6000 RPM if I remember this article correctly. They also didn't do anything under the oil pan either, such an engine especially as it starts getting on the 6000 RPM line could benefit from a windage tray, a rear pan baffle and a crank scraper, this would minimally insure that the oil got pulled out of spinning crank, put under the tray to lose the entrained air, and the baffle helps keep it in the sump instead of the rear crank counterweight when accelerating the car hard. These are things a dyno doesn't do so it's not so critical to have these parts in the bottom end when the engine isn't being maneuvered by the vehicle.
For a few dollars more you can buy one with vortec heads check this link out >>> 5.7 Ltr - 350 C.I.D. - GM ENGINE 1996-2002 New 12530283
<<<. This is a 4 bolt Vortec with a roller cam. The ponies can easily be pumped up with an aftermarket roller, this gets around the flat tappet break-in issues and eliminates the downstream risk of smoking lobes and tappets because you can't get high zinc oil. Since you would stick Vortec heads on the low end Goodwrench anyway the 600 bucks on top of the Goodwrench closes a lot of the cost gap and you end up with a much stouter 4 bolt bottom end. The cam, intake and headers would be the same for either, so for about 400 dollars cost delta you have a much better engine, and no extra heads taking up garage space. The only addition to get this into pre-1986 vehicle will be the purchase of a one piece rear seal mating flexplate and an electric fuel pump.
Really for an entry level upper end high performance 350 engine you've got a lot of choices and the 12530283 as a new 4 bolt block with Vortec heads a very good starting place.