I recently hrydrolocked my motor(4.0 ohv) and believe I bent a rod because the engine won't turn over by the crank with the plugs removed. So I figured it would be a good opportunity to do a full overhaul on my 300k+ mile motor. And while I'm in there, may as well go all out! So my plan from reading posts from you guys, is as follows: my 95tm block bored as little as possible, comp 422 cam, my 95tm heads checked and milled for 988 springs by a shop, and mildly p&p by yours truly, along with the lower intake, 91tm pistons to up the compression, New crank, bearings, all seals and all gaskets. And of course a snorkel to prevent this happening again. I have a few questions that I need help with though. I have read that the 91tm pistons are heavier than mine. Do I need to get the corresponding year crankshaft to properly balance the engine? Will I immediately need a tune before I can drive it? And are there any other issues that I will run into? Its a 96 with obd2. And how long before I can rag on it again? I love my offloading.Thank you for your help and I'm sure i will have more questions as I go along.