I would think under 0.050 t slot would be getting on the too small .
IIRC my 1050 is 0.059 or a hair smaller. This is where I have it now on my 505 , may have been a hair bigger on my 440 . 505 pulls harder on carb . On the 440 it was #82F #98R , on the 505 I only needed to go #100 rear . It has a PV
Have you altered the IFR jetting , I took mine from 0.045 to 0.044 and lowered it . Was noticeable . I also increased to PVCR from 0.070 - 0.073
I do think I need to increase the T slot back a hair for street driving , though it is winter here and I will see how it goes as it warms up .
I am running the 1050SP sportsman aluminium 4500 .
Good luck . Knowing it will never be perfect I am looking for close , 90%

Tex