273 2bbl turn into Commando or is 318 better?

The Edelbrock performer 318 and their 600 CFM carb are almost a perfect match for the 318. They are also easy to find and relatively cheap. Within the last year I bought the intake used for $60 and a "ran when pulled last week" carb, also for $60.

At those kinds of prices you could pay for shipping!

I bett you could get them new, but they are over $200 each that way.

I have a running 318 that already has the same intake and carb, and when I swapped the carb out for the one I just bought, it fired right up.

With those parts, you will see a moderate permormance gian, but not overload the factory cam. However, you can still put in a moderate cam (like a .450 ish lift) and still be in the range of the carb and intake.

Headers and duals will get you another increase.

Put it all together and you've added about 100 HP, and still not gotten into any head work. I'd reccoment 302 heads, or a complete 86 and up roller cam 302 head motor, as they are IMO, actually a better starting point than earlier mills.