Look at the engine number under the generator stand. It should start with an "H". That is a 1500 engine case.
The 1500 engine case isn't the best, but there's nothing wrong with it either. If you just want a stock engine, rebuild it. You will have to upgrade it to 1600cc because the original 1500 pistons and cylinders haven't been available for at least 3 decades.
If you don't like the autostick and you want to convert to a 4 speed, it makes no sense to drive it while waiting for it to blow up. Convert it now.
You'll have to rip out all the autostick parts, including the tank on the right.
Besides getting a manual gearbox, you MUST buy a shift rod from a manual trans car. Only one from a 68-72 Ghia/Beetle/Super Beetle will work.
A set of 4 speed pedals.
You need to look into your pan to see if it has a clutch tube in it. If it doesn't, you will have to install one.