good heads to get me by?

The 273 is a bit small for streetable and enjoyable HP at that level. Your much better off with the 360.
The head ID for 308 heads is located under the heads twin runners. (In the middle)

A nice combo for that approx HP out of a 360 would be something like;

Stock engine with a good dual plane, 650 cfm carb, a cam of approx 230 @ 050 duration and headers into a 2-1/2 exhaust. Depending on the 360 you get, some head milling may be in order to achieve about a 9 - 9.5-1 max ratio.