Pressurising the tank will not solve your problems because the pressure will be inconsistent ... causing problems with fuel supply.

You would need to fit a regulator between tank and carb. There are several regulators on the market.

Alternatively, you could fit a Perry pump to the model. These work well and reliably, delivering a constant head to the carb.

Alternatively, alternatively, you could adapt a Walbro carb to provide a regulated fuel supply for your carb. This is easy to do ... once you know what you are doing!

My advice would be to either buy a better engine or else buy a Perry pump.