Since I too rarely rarely monitor this or any other board, being too busy with restoring and transferring everybody's orphan format tapes and discs, what I can tell you is what we do here for any kind of enclosed tape format is to unwind them onto large-(NAB)-hub reels (yes, they do come in eighth-inch and seven-and-eight-inch sizes) and just rework any good reel deck (conventional, or, we use duplication-style).
The main reason to use a reel deck is simple: a good reel deck will GENERALLY have a more stable speed than will cassette, cartridge or other enclosure-based tape deck transports.
Make sure you start off with a reel deck that can handle the extremely thin (by reel tape standards) 12, 9 or 6 μM thickness tape without stretching it when threading through the mechanism.
**IMPORTANT** NEVER NEVER NEVER USE FAST FORWARD OR FAST REWIND ON TAPES FROM A CARTRIDGE OR CASSETTE!! Only use the low-torque PLAY to wind back and forth (for recording retakes etc) but without threading through the transport mechanism, as well as to load the tape onto the reel in the first place from the cartridge or cassette. To do otherwise will stretch out the extremely thin tape, rendering it unusable afterward
Put the right eighth-inch whatever-track heads you need (2-track, 4-track, Sansui 6 track, (that's always fun to deal with) etc onto the reel to reel along with the correct size guides, and calibrate your head's rack wrap height azimuth and zenith like you'd set up any other analog tape deck prior to transfer.
And for the individual tapes, get a reel of 12, 9 or 6 μM leader tape (matching the thickness to the tape itself) and an eighth-inch (0.15) quarter-inch or half-inch splicing block along with some of the ultrathin VHS/Beta splicing tape since the normal reel to reel splicing tape will be too thick.
C A R E F U L L Y remove whatever leader is there when you took the tape off the hubs and wound it out of the cartridge onto a reel, splice a few feet of leader onto the head of the tape, load onto your new Frankenreel tape player load your tape, set up your computer for recording and go to town.
Talking about Akai multitracks, we do the same for the analog Akai 1212 and 1214 tapes.
As far as Where to Get Heads:
John French Magnetics in New Jersey makes any kind of head you need as long as A) he has the specs in his MASSIVE file of historical tape head designs, or B) you can get him the head specs in the unlikely event he doesn't.
Other than that, most semi-pro and consumer heads can be had by whatever they call Nortronics these days as well as most of their peers.
Maybe that'll save you guys some money and give you some pointers transferring this stuff yourself.
