Building out a 273 recommendations

If you put in a big cam and bigger carb, it will be almost un-driveable unless you constantly rev the motor. Lots of valve overlap gives the stumbly "race car" sound that many prefer but also pours out noxious fumes and gives terrible mileage. The Tesla drivers in Silicon Valley will sneer at you.

In my 1965 273 (originally 2 bbl), I put a hydraulic "RV/Torquer" cam (0.422"/0.440" lift), which is a bit bigger than the Commando cam, and Rhoads leak-down lifters so it idles smooth. I don't like adjusting valves. I get enough of that with my M-B diesels. I used shorter "340 TA" ball & cup pushrods.

I 3rd the suggestion to lose the points. You can get a new HEI distributor for $45 on ebay, plus a $20 e-core coil. Some install a 72+ Mopar ignition, but that is much more effort, and usually much more expensive, plus an older design (requires a ballast).