Changing Starting Strength to Sets of 12
The heart of Starting Strength is an interdependent synthesis of the following factors:
- Progressive overload every workout
- Squatting every workout
- Focus on few compound lifts
- Sets of 5
There are other contributing elements, but I'd argue those are the core of the program. The key is that each element depends on the others. Changing sets of 5 to sets of 12 cannot be done without upsetting the balance: the progressive overload scheme will have to change, since sets of 12 respond differently than fives to increased weight. Total volume will go way up, which might affect later sets in the workout, especially the power cleans.
Your Specific Situation
Do not do snatches in sets of 8. First of all, sets of 8 in the snatch are ridiculous for anything except conditioning or sport-specific training for Olympic lifting. Second of all, snatches aren't in Starting Strength--and power cleans--which are in Starting Strength--are a totally different animal with sets of more than 5, just like snatches.
If you want a hypertrophy program, a hypertrophy program would be a better choice than Starting Strength with a different rep range slapped on the box. Hypertrophy-specific programs add volume and hypertrophy-rep-range work using more appropriate exercise selection and ordering than this modified pseudoprogram. Or, just do Starting Strength and eat a lot. People get bigger doing that.