I'm in the same boat as the original poster. Maybe he can avoid my mistakes..
My '69 is a bona-fide granny car, 307/pg/ps/ac/pb. I have all the paperwork, including every time she had the oil changed and bought tires...when I got it, the original 307 was shot (from sitting up). I decided on a resto-mod, with a 468 between the fenders, 12 bolt (or a 9") out back, etc., etc. Like the original poster, I was (and still am) kinda on the fence about what to do with the car.
I've got 80% of the engine in boxes, ready for assembly. But to finish my car right (i.e. suspension mods, complete rear end assembly, changing from column shift to floor and cutting holes, figuring out how to be able to adjust valves on a BBC car with a/c, buying all the brackets, fuel line conversion, radiator, the list goes on) is gonna cost a TON. I could stick a nice little SBC right back in and drive it for nearly nothing compared to the cost of the BBC conversion, and just enjoy cruising with the a/c on (which, still worked when i pulled the 307). And now, that's about what I've decided to do.
To summarize...I was in your situation (or close), and chose to restomod, only to get halfway in and see that I could have fixed my chevelle back nearly stock AND afford a cheap beater hot rod, for the same (or probably less) money than the restomod route. It's a lot cheaper and easier to build a dedicated beater race car than to try and make a stock chevelle into a half-way race car.
But it's your car, and your decision...