273 hp specs

Stock cam per NHRA is .415/.425 lift
Ok, I've not rebuild the top end of a motor before so I'm not sure what todo with that info, but thank you in advance for future reference.

I am currently trying to get the stock specs to fill out a compression calculator, and I believe I need most of the info I listed about and stock it should show 8.8:1 compression ratio. However information has some key gaps and contradictories.

If anyone can show me the stock 273 specs that equal 8.8:1 in a compression calculator I would be greatful and will be able to compair aftermarket heads and ensure I keep the compression I have or improve upon it.

Thanks