It seems this IS the small-block Chevy! I have one in my '70 Camaro.
The difference between the 307 and the 327 is the size of the bore: The 327 has a 4" dia. bore, and the 307 has a 3 7/8" dia. bore. You can't bore a 307 block to the 4" bore, there isn't enough wall thickness.
The 307 uses heads that have ports meant for economy, rather than performance. Heads are swappable, though.
Now for the good news: The crank and rods are the same as the later 327, and there isn't THAT much difference in bore size. But when it comes time to put insurance on this baby, there's a whole world of difference in what you pay for a 307 vs. 327!!
This is an EXCELLENT engine for you to start with - great for street use, parts easy to come by, and no 'high performance' stigma associated with it, at least in the eyes of the insurance companies. But it is still a powerful engine. More power than you or I will find a legal use for, that is for sure!
What you'll want to do is a high quality, more-or-less stock-type rebuild.
Smokey Yunick said it best: "I've looked at these trick of the week engines, and when you open them up, - the really important stuff - the ring seal, port prep and valve job were laughable".
So to Smokey, the "Really important stuff" is the ring seal, port prep and valve job. That's where to concentrate your time and effort!
Have you gone around Summit Racing and PAW sites? You can find parts there at reasonable prices for high quality stuff. If you're really set on spending money somewhere, consider the 'gapless' rings.
Is your Dad going to help you with this? Bet he will if you only ask. Lastly, consider fuel injection. You can get an FI set up off of a 305 for not a whole lot of money if you shop around. Better mileage, more power, and the GM ECM is programmable. Just check out
http://moates.net
Type to you again soon!