my advice would be to sell all the tires, wheels, and spacers
buy a wheel/tire package that you want. Preferrably in some real sizes.
but i guess if you wanna continue down this path for some reason:
https://www.tsw.com/alloy_wheels_nur...hp#wheel-specs
Thats the size sheet for TSW Nurburgings.
You said the fronts are 19x9.5 +41, that is listed on there so it appears correct. Is is roughly the same as a stock nismo front (19x9.5 +40)
If you want to match the garbage spec of an OEM nismo you can get a 19x10.5 +25.
I'm sure your 275 and 305 tires will work with those sizes