150 is the absolute max. I try to avoid designing to the maximum. also with Vsat at 1V, 300 mA at 50% duty cycle, you will see 150mW dissipation. This is the spec'd max also. I'd avoid it.
why use an opto? you aren't getting isolation. why not just use a couple of transistors?
Using optos gets me a nice isolation with the HV and I can mux the digit select with only 3 pins. I wonder if there are higher current optos out there?
unless there are more optos that aren't shown, you are only getting isolation on the 2 CA pins and none of the others. To me, isolation isn't a percentage thing - either you have it or you don.t. also, the power supply needs to be isolated.
when I design isolated circuits, I create a "dmz" that has no electrical connections across it. including the power supply.