I just rebuilt a 307 for my friend...got advice here and it all made sense. We were in the same boat...we had the 307, didnt want to buy a whole 350...work with what ya got!!

I used the same exact setup with the K1102 cam and 416 heads. The boost in compression using the 416 heads will put some punch into that motor. The 601 heads with the smaller cc would make the compression a bit too high for my taste. The Summit K1102 is a great match for the 307 with those heads, it will give good torque and good driveability.

Your other questions:
Intake - 2101 or similar dual plane aluminum will be great.
HEI - perfect.
Carb - 650 is fine, maybe a bit big, you can always jet it down...a 600 should be perfect.

Also, a decent set of headers will be worth some extra power.

You'll have a nice street motor when its done.

Good luck!