sell the 350 block to fund some hot rod parts for the complete 307. It will make a very good motor for your truck.
Depending on which 305 heads you got (casting number) they can be turned into a fairly decent street perf head with generous hand porting. (don't be shy, lean on that die grinder) And that combined with the small chamber will wake up the 307.
when you get the heads all tuned up, reinstall on the 307 with a thin felpro 1094 head gasket.
The best of the 305 heads to start with are the 4416 castings. Best when generously home/hand ported with 1.94" valves added.
Mild, moderate hyd cam, hi rise dual plane 600-750carb headers. You will be suprised how good it runs.
when you hot rod a 307 with improved compression ratio 9.8-10:1 and added improved port air flow it makes a lot lot more power than stock.
Much like a 327. A lot less fuss.
Spend the money where it will do the most good.
Last edited by F-BIRD'88; 01-28-2013 at 10:36 AM.