Idea for a DD

[72truckman]

This is a little off topic for this thread but i couldnt think of any better sources to ask... I have the oppurtunity to buy an all original 1965 nova ss with a mild 350 and a powerglide. The paint is new and the interior is flawless. and it has no rust. and its dirt cheap.
What kind of mileage do you guys think i could pull with this if i dropped in say a 200r4 and a 550cfm carb w/efi? I need a new daily driver and i am looking for any alternative to a honda