The thing you can't compare is that the hobbit and express carbs are of a completely different type. One is a slide carb and the other uses a butterfly. Aside from that they are both Keihin and use the same jet sizing designations and so you can use as a rough guideline the size increase based on fuel need.
Say a 78 to a 92 would be the same increase (fuel delivery amount) as an 85 to a ~98. The difference again is that the air boxes are different and the carb is more or less efficient at delivering fuel. They really can't accurately be compared.
If the stock is 85 I would start at a 95 if they are available and work from there.
Also the ignorant remark about the oil pump having cavitation is ridiculous when you realize that it is pumping oil that does not contain air, the pump does not use an impeller of any sort to create cavitation and unless the tank were to run empty or the lines removed and not properly bled after install it is impossible to draw air. The stock oil injection does pump rich but is well made and uses quality hardened parts. The only thing dangerous about it is the mechanic screwing with it. The autochoke works pretty well when clean and properly connected also.