From my perspective, I wouldn't mess with building a late model 302 block, they are weak. Why put a forged rotating assembly ($1500+) in a block that can't reliably take 500hp? Personally I would build a stroked 351W, a 393 is CHEAP to build, stock 351W length rods, standard 302 pistons, only thing special is the stroker crank. Using decent parts a 393 could be built for less money and handle a lot more power in the end. Heck even a 408 or 418 are pretty cheap to build. With a 393 or bigger stroker 500rwhp is easy even n/a.
If you want to keep the 302 deck height, keep your 289 find out what all is done to it and put new gaskets in it. It is considerably stronger than a late model 302 block, girdles will help keep the caps from moving around but in the end they just hold the pieces together when the block splits. I'd hate to see you spend $1500+ on a rotating assembly to have it destroyed when the block splits.
I really like KB blowers but on a 302 they leave a lot to be desired, they aren't intercooled and there is no easy way to do it, you are limited to less than ideal lower intakes, they support very limited HP and to get a 302 to reliably take 500+hp you need a $1600 aftermarket block.
I would do a stroked 351W, leave it carb'd and have a ton of fun. If you want to do an EFI swap then that would be fine also but a properly tuned carb can see 20+ MPG with OD on the highway.
What are you wanting to do with the car?