need engine advice

Hi folks. I've been lurking around here for a while, thinking about modifying the '66 coupe that I bought last summer for a daily driver. It's a NOM 2v 289 C4, AFAIK completely stock, with 2" duals and unidentified turbo mufflers. Oh, yeah. It does have the Pertronix distributor conversion.

I'm coming back to Ford territory after 20+ years of Chevys (I still have one). My high school cruiser/bracket racer was a '65 fastback, but I've forgotten most everything I knew about small-block Fords back then.

Anyhow, I do a good bit of highway cruising, so I plan to go with an AOD soon. Short-term planned engine mods include carb/manifold, cam swap, and possibly shorty headers. I'm looking for low-mid torque and fuel economy on a limited budget (I might consider investing in a roller cam setup if $/power ratio is right). What can I expect to get out of a stock-head 289 in this application? What do you think of the hwy mileage potential? Any specific parts recommendations? Should I just go with a carbed 5.0 engine along with the AOD? I don't really want to, but if were the best long-term move...

Thanks,
Barry

How are the heads on a 5.0? And are they pretty much all the same? I know they're not great, but will they clean up and be better than the 289 pieces? I'll probably never see the high side of 5000rpm with this engine.

I'll have to look into the 5-spd conversion. I'd pay a mileage price for an auto, though, since every other vehicle I own is manual trans.