To develop a Simulink model for assessing the performance, combustion, and emission characteristics of a spark-ignition (SI) engine using a gasoline-biogas dual fuel strategy, I have outlined the necessary components and the corresponding useful Simulink blocks. 
Key Components of the Model: 
- Engine Model 
 - Fuel System 
 - Ignition System 
 - Exhaust System 
 - Control System 
 - Performance Metrics 
 - Torque and Power Output 
 - Fuel Efficiency 
 
Suggested Simulink Blocks 
- Signal Builder: For input signals like throttle position and engine speed. 
 - MATLAB Function: For custom calculations and logic. 
 - Integrator: To model dynamics and state changes. 
 - Gain: For scaling signals. 
 - Lookup Table: To model non-linear relationships like fuel maps. 
 - Sum: For adding or subtracting signals. 
 - Product: For multiplying signals. 
 - Scope: For visualizing outputs like torque, power, and emissions. 
 - Subsystem: To organize and encapsulate parts of the model. 
 
For more information kindly refer following MathWorks documentation. 
I hope this will be helpful.