If 2" is the size limit, the A17 is actually 2 1/8" nominal size, the 17 being the major diameter in 1/8's of an inch
Even if you choose to buy elsewhere, the chart linked below should help choose the lamp you want.
E26/27 is the medium base.

Here is a link that might be useful: Chart

Hi bus_driver,

A belated thanks for your advice and the chart you linked. I appreciate the point about the A17 being a little too large. I'd love to find a 100 watt equivalent bulb but it looks like 60 watts will be the highest I can find.

Thanks again.