why won't the hood close? they put hundreds of thousands of those turds in G bodies all thru the 80's.
as for the best way to get performance out of a 307- i'd say to just replace it with an Olds 350 or 455 and be done with it. they will bolt right in using the stock mounts and tranny, and the 350 will use all of the stock accessory brackets. the 455 will need a few different brackets, but nothing that's not easy to find in the boneyard.