FWIW I started fixing up my 305 in my Cutlass wagon which had been rebuilt by the previous owner and had about 35,000 on it. I added a Crane 266 cam that had .440 lift, air gap dual plane intake, Edelbrock 600 carb, Pertronix HEI internals upgrade, headers and a single 3" exhaust. The lower torque output of the smaller engine was compounded by the crazy 2.41 gas mileage rear gears but it still ran ok, turning 15.90s @ 88 mph in the 1/4 mile at sea level, near 2 seconds faster than in stock form which was 17.70s at sea level. Remember, the 305 was a "performance" motor used in IROC Camaros to Monte's and for a small motor with lousy flowing parts it actually does ok with some slight upgrades. With stock heads it's really limited to just how much power it can make, the TPI intake, heads and cam really woke up the motor for the IROCS.
In comparison in high school I had a Nova that came from the factory with a 307 SBC. With similar upgrades and a set of freshened up camel hump heads with the factory 2.73 gears it was slower at 16.0 in the 1/4 because the 305 makes more torque than a 307. My guess is that's why GM went with that bore and stroke combo for the generic Chevy small cube motor. All of my performance builds have had 406 SBC's and one of those eventually replaced the 305 in my wagon. The 305 got about 21 mpg at 65 mph whereas the 406 with mildly ported factory 400 heads, a .510 lift cam that was a Comp XE268 with 1.6 rockers, and the same intake, exhaust system, and 2.41 gears ran 14.20s @ 97 mph in the 1/4 and got 18 mpg. Eventually I swapped in a 3.42 rear axle and it ran 13.60s in the 1/4. Cubic inches makes a big difference.
So, really a 305 isn't that bad of a motor, but... Another project I have is a 73 Nova restomod project with a lot of planned hidden upgrades. The car was originally a 350 2bbl./ 3 speed, but I've decided to clone the '73 "performance" 245 hp 350 with stickers, intake, carb, etc. Under all the stickers and orange paint will actually be a disguised 406 with the same 268 cam that was in the wagon. On the outside, unless someone looks at the harmonic balancer you would never know it isn't a 350. As others have said you can easily clone the 305 with a bigger motor under the blue paint and such. A rebuild will essentially cost the same and you'll end up with a bunch more torque and horse power even with mild parts, and if you decide to upgrade to even better parts down the road the power potential is even greater and less limited.
Good luck with the project!
in my '86 MCSS!!!!
