The book "Custom Line Atlas Layouts HO Scale Railroads" (Armstrong, John H. & Thaddeus Stepak, 2nd ed. 1971, Atlas) has two scissors wye templates, one for a 45-deg crossing and one for a 60-deg crossing. The 45 would seem to suit your application better; it uses #4-1/2 switches on the main and the standard Atlas wye switch which is a #6 on either side.
:B~)