Pulling the engine much easier than you might think. If you’ve never done it - it might seem overwhelming but it’s not. You can do old fashion way if need be on an oak tree branch or run a 4x6 across 3 or 4 trusses in a garage or pole barn. Then just a couple vertical 4x4’s under the truss on each side of the boat where you’re lifting from. Prep time to pull shouldn’t be much more than 45 min to an hour.

If you have the motor torn down to the picture in the first post then it cant be the oil pump....there's nothing driving it without a distributor.....so in my head its either a bent connecting rod or damaged crank.
Only other thing i can think of that could bind it would be if a chunk of metal come off something and got wedged into the cam gear teeth and is stuck there...that would lock up the motor once it hits the chain....and you would spin it close to 180 each way before binding...