Lot of choices
Well, just for conversation, it's best to optimize everything.
If that works well, you can scale back, keeping reliable reception.
Remember to factor in a little extra for those rain-days.
The 1.2 meter CM dish is your best.
The original feedhorn it came with is probably your best.
I would prefer to use the SatAV PLL Standard LNBF, but that conflicts with several of your desires.
Tron suggested the bandstacked LNB from a SuperDish.
I like that.
You have some SC bandstacked LNBs?
If it'll bolt on, I'd try that.
Im currently stalled on a project to convert PLL LNBFs to LNBs.
Single output, and dual output.
Should be exceptional.
You might also go with a stock single- or dual- output PLL LNBF.
Just go with the built in feedhorn.
Again, that's easy to test.
Fortec 1.2m with QPH-031 and a SG2100
I hope you have abandoned that plan.
Nothing in that soup I can recommend.