If you add oil to the fuel you will lean out the air fuel mixture.
I would put in a #240 - #250 main jet, depending on your elevation, temperature and then plug chop to confirm.
As an example changing from 32:1 to 25:1 needs one size bigger main.
The oil injection adds oil directly into the air stream in the carby.
Adding oil to the gas changes the amount of fuel that passes through the jets, because oil takes its place.
You will run lean if you do not increase your jet size.