[Mike]

Not aware of there use on the 307 but guess anythings possible.
Here's what I've got:
462624.....75-86...350/400......76cc chamber, 1.72/1.5, 1.94/1.5 or 2.02/1.6 valves

Where did you see the 307 shown for these heads?

 

[Mike]

Be careful with the compression ratio.
You haven't posted your current engine combo (piston specs,cam specs,etc) so we don't know where you are regarding c/r.
Go too high and your into higher octane gas.
If this is a stock engine configuration ,post the engine id code and the block casting number and casting date as shown

 

[Mike]

TDD 72 350 Truck 175 LS-9 Manual 4-Brl C 10 & C 20

 

[Mike]

OK ,I'm back.
Here's the NHRA specs for Chevy's 72 lineup - http://www.nhra.net/tech_specs/engine/blueprints/CHEV-72.rtf

Keep in mind these are blueprint specs.
Appears that if you go to a 62cc head ,you'll be close to 10:1 c/r

 

[Mike]

Look at post #9.
It's your engine id code ,not the 1dd you posted.