67 plymouth barracuda fastback 273/727

If you like the "stock" look of your car, there are many things you can do, performance wise, and have it still appear stock. You coud do engine swap, and save the 273 for a latter rebuild. Upgrade your brakes and suspension as well. After you've had your "fun" with it, you could always return it back to "stock".
BTW, welcome aboard form the mitten state!