To answer your question on using a conversion to obtain your FAA certs, the answer is "no", with a big "but".
There is no standard conversion and (from my and my friends limited experience getting our ATP's) the FAA views military flight time as it is logged. No conversion factor allowed.
That said, some time has to be reconstructed. The USN/USMC doesn't log cross-country time for example. My FAA examiner (FSDO employee, not a DE), accepted my XC time reconstruction, and for that matter, all my time on my application, without checking my logbook. For my part, I put down my logged times exactly from my logbooks without conversion or fudging, and I brought documentation for the XC time reconstruction - flight grade forms which noted routes of flight, copies of NAVFLIRS (flight manifests/data forms) which show landing locations, etc. The FAA guy didn't look at any of it, but it was one less thing to worry about during the checkride.
All certs up through Commercial/Inst only require an equivalency exam (based on the commercial test) with no flight time requirements other than a limited currency requirement, IF you are on active flying status within the previous 12 months. The rules are in the CFR 14 (FARs) 61.73.
Inst ratings added to a certificate or obtained at the same time as the Comm is obtained only require proof of a current military check. Add on commercial certs don't require you to retake the equivalency exam.
So when I went in to add a Comm SEL to my HELO/MEL ticket, all I had to show was that I was on flight status, had 10 PIC hours in the previous 12 months in an SEL airplane, and that I had a current PIC check.
ATP, type ratings, and certs based on military experience when you haven't been on military flight status in the previous 12 months require FAA proficiency checks, etc. as shown in 61.73.
Tell your buddy good luck, but if he/she is getting a cert to fly in GA aircraft (like I originally did), to be sure that he/she gets some instruction from a CFI if he/she doesn't have any GA experience. A little competent instruction will go a long way to ensure safe flying.