I don't know that adjusted costs of individual research projects are going to be informative, if that's what you're looking for -- they are apples and oranges between the research of today and in the past. You may be able to find historical data on total R&D spending, either in (adjusted) currency or as a percentage of GDP. Check out the NSF research reports e.g.
https://ncses.nsf.gov/pubs/nsb20221.
