Loading varies with the phono stage, the overall system, and one's taste, of course. And like anything in vinyl, it can always be optimized by fine changes, IMO. Whether one really needs to is another question. Playing with this VAC, I find changes of 15 ohms to make worthwhile differences so I've blown a load of cash on Vishays from Michael Percy, mainly because it's so easy to experiment. but I could have gotten by with fewer options.
I'd guess your Ortofon would be quite happy at 100 ohms. Would it be happier at 125? Maybe but it might very well not matter. I have two Ortofons and I like them both at 25 x DCR.
BTW, how do you like the Bronze? I've been interested in that cartridge--seems like it would be very meaty and musical with good detail.
VAC did the mod. It was Brent's clever idea and he did a beautiful job. Resistor value x 10 gives me loading value, so it's a breeze.
Best,
Bill