You don't have to spend a fortune on a teen to get performance.The main thing going against you are the pistons, usually down the hole quite far resulting in low compression.Some KB'S will sort out that problem.Next the cylinder heads, for low bucks I like the the factory J castings(for a non Magnum application) cleaned up with 2.02 or 1.92 valves with new guides,springs,retainers and some machine work(do a bowl port at the minimum),some ARP rod bolts.Find some 273 solid lifter valve gear from a junker or second hand and throw in a nice solid lift cam and you will be enjoying the teen the way it should have been assembled from the factory.