This is 1960’s tech and it they brought it back into service today, it would still be the baddest boy on the block and it would still give the enemy fits.
It's actually 1950's tech. The SR-71 was based on the A-11 and A-12, both of which began development in the late 1950's. One thing I didn't know is that the SR-71 had some significant radar evading stealth technology.
http://en.wikipedia.org/wiki/Lockheed_A-12
On a related note, the Saturn rocket booster and its F1 engine also began development in the 1950's, well before JFK's "Moon" speech.