I know I'm late to the party, but that's not head cracks, those are pre chamber cracks.
You can replace the prechambers they are just lightly pressed in.
Shims are included with alot of kits.
They are used if you need to take material off of the top of the block.
The shim does not look like a head gasket.
If you have 2 head gaskets someone messed up.
You will need to check clearances on the pistons.
It's in the service manual what the clearances...
That is a 843 with a Perkins Diesel engine.
They never put the Perkins in anything smaller.
Smaller units got a Deutz Diesel, Ford gasoline, or Kubota Diesel.
It's not Gasoline (injectors) and no plugs.
It's not a Deutz, they are Air cooled.
And that is 1000% not a Kubota engine, I have several...
That is a 843 with a Perkins Diesel engine.
They never put the Perkins in anything smaller.
Smaller units got a Deutz Diesel, Ford gasoline, or Kubota Diesel.
It's not Gasoline (injectors) and no plugs.
It's not a Deutz, they are Air cooled.
And that is 1000% not a Kubota engine, I have several...
I'm with Al Jones on this, post #22.
You can all so drive moisture out of switches and components with simple WD40.
Just heat if frozen and spray internals and contact points.
The engine ID is stamped on the flat right next to the injection pump facing up.
All 743's came factory equipped with a V1702IDI engine.
Don't rebuild it, replace it with a V2203DI, it will be the best thing you can do.
I did mine years ago and it's worked its tail end off since then!
Your making the automatic assumption that it has a parking brake that works as designed, some don't and the axles are controlled by solenoids some don't.
One other thing to consider, were your snow tires sipped?
If not that alone adds a ton of help to snowtires especially on ice.
I've done several different and ended up going back to chains.
If your chains aren't heavy 2 link chains that's why you think they are rough, I really can't feel mine...
No you can't really pull the gear case apart while the engine is in there, your going to need to pull it.
Do you have the repair manual for the engine?