What kind of gas mileage does an ls1 in an elky have, ballpark?

If a ls1 gets similar mileage to that of a vortec 454 wich one has better potential for mucho horses. Plus used V454's are cheaper and easier to find.
Or if I rebuilt the stock 305 what kind of ponies could I get out of it?
If you "bore" out the ci to a 350 or 383 would the smog be the same, or would I need a different smog setup?
This 79 el is my first car that is-not-smog exempt and allready seem's like a pain in the A@#!!!!

The LS1 in my '02 Camaro gets about 20mpg. You cannot bore the 305 to a 350 there is not enough cylinder wall to do that. You would need to get a 350 block. All of the brackets etc from your 305 will bolt to the 350 unless you get some strange block. A 383 is from a 350 block and getting a crank shaft that increases the stroke of the rotating assembly to 383.

The 305 would be limited in what you could get out if it. If you do some searches here you can see what some people have said could be pulled from it. I don't know the answer to that. Or the answer to what you could do to a Vortec 454. I'm not real familiar with them other then knowing they are based on the same setup as the LS1.

Realize with your Elky after a certain point the HP will just be for bragging. Lighting up the tires is pretty easy with an Elky.