Like John said find out what was in the 78 and try to replicate that, they might not be the original pups. Even if you do buy the same they will probably not sound identical in your Love Rock due to different wood combinations.
I've got replacement pickups in all my guitars depending on what sound I wanted
Seymour Duncan Seth Lovers in my 335 for that ultra authentic alnico 2 PAF sound, overdrive beautifully but are a deemed to be low output in terms of dc resistance but don't be fooled they're very loud.
My SG has Gibson 57's in it don't know much about them but I think they're another classic type pup, idea for angus impressions!
LR has ended up with SD Pearly Gates (rumour has it they were designed for Billy Gibbons) as I wanted something that was a little ruder. Also tried 59's and Phat Cats in this guitar before settling on PG's.
That just my Tokais my strat, tele, gretsch have all gone through pup changes!
I had a LP that had Burstbucker 5 in it, prefered them BB3's. There are various BB's available depending on the tone your after.
I would suggest going over to the Seymour Duncan site and having a listen to some clips
http://www.seymourduncan.com/comparetones
Also join their forum
http://www.seymourduncan.com/forum/ and ask them to recommend something based of what the 78 sounded like. They're a really knowledgeable bunch on not just SD's but Gibsons, Dimarzios and a whole heap of pup makers you've probably never heard of. They're a friendly bunch who helped me out no end when I started off pup changing.
If your handy with a soldering iron pup changing isn't expensive or difficult, buy a secondhand pickup off the forum or ebay, try it, if you don't like it sell it and move onto the next idea.