To that end, although the later 350 can be swapped in, it's better if it's done as an entire assembly from intake to pan to minimize problems. For the '87-and-later 305 cars, a "roller 350" bolts in and only needs bigger injectors and a 350 PROM for the computer. Regardless of the engine you swap in, be sure that you have a cam designed for fuel injection if you are running TPI, or tuning will be a nightmare.
Automatic trans-equipped GTAs-and many auto trans IROCs-come with 350s, as do some of the "big" sedans of the era, such as police cars and taxis. The big cars are throttle-body injected instead of Tuned Port. Another excellent source for a junkyard 350 is a mid '90's Vortec truck engine. Though it requires a Vortec-pattern intake-available from Scoggin-Dickey or Edelbrock-to run your TPI, the engine is otherwise a bolt-in. You can also swap the earlier bolt-pattern heads onto the Vortech block, so no other modifications will be necessary. In addition, some Vortec truck blocks are not drilled and tapped for the hydraulic roller cam spider, which can be easily done if you're rebuilding.
To find a 350 engine in an F-body or taxi, first look for the coolant tubes to the oil cooler. The very rare 1LE 5.0L in Camaros and Firebirds also have this cooler, so check to verify a 350 by looking on the driver side near the distributor, behind the cylinder head. The block will have either a "5.0" for the 305, or "5.7" for the 350 (see photo) cast into the block.

The overhead console has a built-in flashlight, although this one's map pocket has been torn down. This feature was available in coupe or T-top versions, which do not interchange. To remove it, take out the screws under the dome light lens and slide the entire console backward. Make sure to get the wiring and mounting screws. You'll have to cut your headliner to put it in.
Moving on to exhaust matters, on a few missions as an automotive recycler I have spotted the '89-and-later dual-cat y-pipe. Although in GM ratings they are worth 10 extra hp, converting to a dual cat y-pipe can be a hassle, as it requires the later "high-flow" exhaust manifolds and a different after-cat system. With that said, many aftermarket exhaust manufacturers offer better flowing and smog-legal headers, y-pipes and after-cats for these cars. Though power increases may be marginal on a stone stock 305, freeing up the exhaust provides a solid foundation on which to build more power with further mods.
Inside Job
Perhaps the biggest issue relating to the value of these cars is the condition of the interior. Most of the "soft" stuff-such as dashes, seats, armrests and consoles-were lightly constructed and easily damaged, so few arrive at the junkyards in presentable condition. Fortunately, excellent resources, such as Hawks Third Gen or YearOne, supply many OEM used or New Old Stock parts to replace discontinued dealer items. A number of troublesome mechanicals, such as convertible top parts, rear hatch pull-down repair kits, door hinge repair kits and sturdier Wonder Bars have been redesigned by Top Down Solutions for added durability.
Since GM was kind enough to design most of its seats with the same bolt pattern, we sourced a good set of air-adjustable GTA-style seats from a Pontiac Sunbird Turbo convertible for $45. After a thorough cleaning with a rental carpet cleaner upholstery tool and a swap to the F-body seat brackets, all wires and air-pump tubes hooked up perfectly-even the color was correct. Another option that looked good were Sunfire seats, which would also have required cleaning and a bracket swap.
The overhead console is one optional interior piece that is usually in good condition because of its location out of harm's way. Incorporating the dome light, the ball-mount map light, mileage and appointment reminder wheels, a stowing flashlight, and a pocket for cell phones or garage door openers, it's not high on the list of "necessity" options, but it gives the car a more "cockpit-like" feel. Beware, as overhead console designs for coupe and T-top cars are different, and will not interchange. These can be scavenged from Camaros as well, but the little flashlight will say "Camaro" on it instead of "Firebird."
Body DoubleMost front-end parts interchange. Fenders from '85-'92 Firebirds will swap, but remember only Trans Ams have front fender vents (just behind the front wheel). Noses and Aero Package components changed mounting type and location in 1985, and again in 1991, so fenders for those year noses and Aero Packages have holes or slots in different places. The basic stampings are the same, and even the '82-'84 fenders can be used with minor modifications. Keep in mind that noses and Aero Packages have usually suffered a hard life by the time they hit the yards.