At a $1,000 limit? Stay with the 318 for a rebuild. Punch it out only if need be. The boreing out of a engine is to clean up the cylinder walls for use, not to increase performance. Your only gaining a few cubes. It's nothing in terms of performance.
IF you can find a low mileage "LA" 360, running, (Non Magnum engine) from a junk yard or known sorce, that would bea good way to go.
(IMO a better way to go.)
You could swing the Carb, intake, heads over and get a new cam.
Once you decide on gears and tire size, I can make a cam recomendation. Right now, it would be to broad area to come up and say, "Use a cam of **** @ 050 with that combo." You'll still have a issue with a torque converter. Do you plan to leave it stock?
This would be a key item on what cam you can getaway
The small carb is not an issue with the 360 and the Torker II. You may miss a little top end power, that's it. While the single plane lacks a little torque over the dual planes (AKA RPM) repurchaseing an intake will eat up about a 5th of your grand alone.
