Sorry for the late reply, thanks everyone!
Wiebke, it sounds like you were lucky to find those perfect matches with your piggies. I'm really hoping Indy will find her perfect companion, too. I'm aware that I probably won't have much of a say in the matter when choosing! I'd just love for her to find a friend she's really happy with.
Claire, it's great to hear about it from a rescue's point of view. How you do the introductions is pretty much how I imaged, and it would be great to have the continued support of the rescue after adoption. I'd be very reluctant to leave Indy to be bonded by the rescue, but I have plenty of space and time (and treats!) so hopefully whoever I adopt from will trust me to bring them home after an initial good meeting. It's a pity you aren't closer, you sound wonderful!
Joey&Gizmo, glad to hear that your bonding turned out well! At the moment I think I'm rather hoping for a "love at first sight" scenario, involving minimal stress for me and the guinea pigs! But I did have to re-bond my two girls after they'd been separated for over a month, so hopefully I'll manage if there is some disagreement to start with.
Lisa, that's a good point. I suppose that's why some rescues advise leaving your piggie for a few days to help them settle into a more natural state? ?/