I will be digitizing some reels from the early 70s...

...in upcoming weeks.  It's my old band and we've just located these old reel-to-reels we made back when dinosaurs roamed the Earth.
 
I haven't heard them yet, but wondered what challenges I'm going to have.  I suspect I'll be able to hook up an old RtoR machine up to my audio interface and simply import, in real time, to SONAR, do some fiddling (not high quality mixed in the first place), and export eventually as MP3.
 
Any of you done this before and have any advice?  Thanks in advance!

I did it.
It's a lot of fun.
Save the raw tracks somewhere safe before you tweak.

bitman made a good point too.  On the way into your DAW no processing or anything. Just capture as they are. All processing should be done post capture.
 
mixmkr if you want to send me the reel I would be happy to have a go at it for you. The baking does not hurt the tape either.  The worst that can happen is that it will still shed after baking.  What you think is useless now can turn into a totally playable tape for one or two passes after baking on the other hand.

I just did this with about 10 1/4" reels of my grandfather playing guitar/singing. The newest tape was pre 1977. I didn't bake these tapes. They were in terrible condition. Very brittle. I assumed I would only get one play out of them. Now that I've done it, I probably could have gotten more than one play. 
 
I wound each tape to an empty reel and then rewound them back before I played them.
 
Other than the occasional tape snapping, it was fairly uneventful. 
 
I did have to clean the machine after every tape. 
 
 
 
https://soundcloud.com/the-grandpa-tapes

Thanks a lot, guys.  I will definitely do the baking.
 
I would go with you, Jeff, but you're in Australia.  I'm in the States.  THambrecht is in Germany.
 
Mettelus, I spend half of my time in Northern Virginia.  Are you in the business, or can you tell me where to get this done?

My friend, Jeff, used this company with great results. 
 
http://thinbrownline.com/

Thanks for the local (USA) recommendations.  I think I'll be going with a "full service", rather than trying to do any of this myself.

Baking tapes is itself dangerous, and may be unnecessary. It depends on how the tapes were stored and how high-quality they are. I'd try it on one reel first. Use a very low temperature and don't over-bake! "Baking" is a misnomer - what you're really doing is drying the tape. 
 
I've read 40-year-old (high-quality) tapes with only some loss of high end, with no preparation other than running the tape at the slowest available speed from end to end, turning it over and running it back at slow speed (rather than using the rewind function, which will stress and stretch - or even break - old tape). This will un-stick the tape from itself and remove moisture from between the layers. You'll want to do this whether you bake first or not. Yes, there will be a fair amount of oxide on the heads and capstan when you're done, so it'll require a thorough cleaning before you start the playback.
 
It's also worth taking the time to perform an azimuth adjustment before you get started. If you don't have instructions on hand for your deck, manuals for most machines can be found online. It's not difficult (just time-consuming), and although normally done with an oscilloscope it's possible to do it using SONAR by carefully turning the adjustment screw by quarter-turns and recording or observing signal strength and spectrum. You'll know when the azimuth is optimal because that position will yield the best signal strength.
 
Try to capture the entire tape on one pass. You want to minimize how many times it drags across the heads, rollers and capstan. Save a backup of that first capture in case you have to go back to it. Once you've got the whole thing in one digital file you can then cut it up and process it any way you like.
 
When I last did this, I did not have the benefit of a good audio editor and had to rely entirely on EQ to get the hiss under control. If I was doing it today, I'd use a good noise remover such as RX, Sound Forge or Adobe Audition. It's amazing how well such programs can work.
 

I THINK it was just 2-track stereo reels, but not sure (maybe 4).  I've only recently located a child of my deceased bandmate, who found the reels at my request, and I won't have them in my possession for another week or so.
 
Meanwhile, I've been researching USA services for this.  I'm in Nebraska half-time and Virginia half-time.  I've found a place in Minnesota, Buffalo NY, Richmond VA.  If anyone here has a specific recommendation or does this themselves I'd be happy to do business.  (Some of the services are pretty "pricey"...)

I have "baked" tapes before using a cardboard box and a 100w light bulb.  Worked like a charm...but just don't go off and leave it, check it frequently to make sure nothing is getting too hot to be dangerous (just use a little common sense).  It worked like a charm for me.
 
edited to add:
 
Of course it has to be an incandescent bulb   :)