NO, actually the other way around. You need 1T bigger 2nd spur gear and 1T bigger 2nd pinion gear ( to compensate 2nd gear ratio so it can go back close to original ratio again ).

If you look closely, (after installing the engine to chassis), 2nd spur gear and 2nd pinion gear are not very close to each other . There is some gap if you compare that gap to the gap between 1st pinion and 1st spur gear.

Second problem, the 2nd spur gear alu. housing is touching the clutchbell ( and sometimes it is also touching the upper plastic brace ). Under stress it will move the engine position to a point where 2nd gears are not touching together anymore.

So you know what to do now.

( I suggest to use longer screws : 3x12mm-14mm for holding rear bulkheads, and 3x10mm for holding engine mounting ).