Hi!
First of all: You have to set all engines by ear! If you cannot do it ...there will be problems. A tach could work but is not that good compared to a the human ear.
The MVVS 12,7cc engine (.77) is set like all other glow engines with a two needle carb. You set the high speed needle first (when you have started the engine and given full power) and then set the low speed needle! The engine should respond immediately when giving full throttle from idle! -If not adjust the low speed needle! -But! remember if you have set the high speed needle too lean from the beginning no tinkering with the idle needle will work! A safe idle speed should be around 1800-2000 rpm with a 13x4 or 13x5 APC prop! Slighly higher (2100.2200 rpm) on a 12x6 or 12x7.
Idle ( drum opening) in the carb should be around 2mm.

Fuel: The older MVVS 12,7cc and 15cc (.77 and .91) engines does not like too much nitro! I have seen and run some that doesn't even like 5% nitro.Those have been impossible to set ! So a good way to start is a fuel containing 20% oil and 80% methanol ...or running 5-10% nitro and at the same time put in a another 0,1mm head shim.

Glow plug: All MVVS glow engines come with either a Nova Rossi 5 or 6 glow plug but equally good is OS 8 or Enya 3-4 or Rossi 3-4, and there are many others that work well too.

Propellers: The MVVS can swing many different sizes of props, from a small 9x8 to a large 15x4 but a 12x6 ,12x7 and ,13x5 are suitable for most sport planes.
Best prop brands are Graupner G-sonic, RAM and APC.