How do you adjust timing on a 273?

I left the vacuum advance disconnected on my '67 273 2 brl.. Base timing at about 18 btdc. They say I loose fuel mileage without the vacuum advance but I never pay any attention to that anyway. I go out of my way to get premium grade ethanol free and pay a premium for it, ignore the mpg, ( focused on smiles per mile ). I rarely drive the car anyway but when I do.. I get great throttle response off the stops and enjoy the drive.
I should mention installing the later ( 73 ) model dual plane intake, that 2 brl. carb with the thick base gasket, and the 73 fuel line routing with the inline filter positioned vertically below the alternator also made a big difference.
Electronic ignition with higher output square back alternator also made a big difference.
You might be surprised at what you can get from a 273 with a small investment in used later model parts.
Did I get waaaay off topic here. Yep. My last sentence probably should have been first sentence. Better performance isn't found in timing adjust alone.