I'd go 3s if possible. It's capable of the torque you need and is already boosted. Put some sort of air/fuel control and boost control and you're all set.

Listen to nelson because he knows. 4a is for corollas IMO.

The only way I'd even consider an "a" series engine in a "t" chassis would be a turbo 7age. But even then it's not worth the money.

Now get a 3s haha.