Best way is to agree to pay for digitizing all of them in the NSS Library. Just call Bill Torode (he doesn't do email well) to coordinate it all, payment, etc. The NSS Library has them all. So, visit Huntsville for awhile..
As of today, the Indiana Cave Survey has 2464 Indiana caving related publications cataloged, with 2373 documents available online. You have to be a member to access these publications, but membership is only $5 a year.