What are the head bolt torque specs for a 1968 Ford Mustang 6 cylinder?
The following is taken from the Ford shop manual concerning the 1967 Mustang: Torque limits for cylinder head bolts, 170 and 200 CID engines: Step 1: 55 Step 2: 65 Step 3: 70-75
The available engines that year were a 200 cubic inch 6 cylinder, a 289 cubic inch 8 cylinder, and a 302 cubic inch 8 cylinder. Assuming you meant a 289, your best bet would probably be to purchase a carb kit, rebuild the carb, and follow the instructions for adjustment. That should give you a baseline to work with.
It depends on the specific sub model you are talking about. The 1968 Ford Mustang Hardtop 390 Thunderbird Special V-8 4-speed with 325 HP has a top speed of 212 km/h (132 mph. While the 1968 Ford Mustang Hardtop 390 Thunderbird Special V-8 Cruise-O-Matic with 325 HP has a top speed of 208 km/h (129 mph). There is no 324 HP variation for the 1968 model.