Don't know if anyone mentioned it yet, but another very typical thing that was done on bands in those days was the hardpanning (either full left, center, or full right) of complete elements. For example drums all fully left, bass fully right, guitar in center with some warbly effects. Should give it a typical oldskool vibe right away. If you have some analog weird guitar pedals lying around, this will be the time to pull them out! And not just for guitars.
Another vote for Izotope Vinyl. Used it on a project once where the client wanted the ending of a song to sound like it was played on a slightly skipping gramophone. Used Vinyl on a separate track parallel style, and compressed and hp/lp it together with the track, and everything glued together in a pretty convincing way. He loved it.
Also, you could use VCC RC tube on everything, cause that one is supposed to sound like an old tube console.
Use a tape plugin with some good wow & flutter and turn up that noise! If you guys don't have one yet, I recommend Toneboosters Reelbus (
http://www.toneboosters.com/tb-reelbus/ ) which costs a ridiculous 10 euros.... but don't let that fool you. It works perfectly fine. It also has an "old and rusty" algorithm which may be suited to the project. Not related to the guy, but I support great plugins for awesome prices.
+1 on putting up a roommic and playing back everything to it. Should add some nice vibes! On a sidenote, cheap ribbonmics aren't actually as bad as one would think. Depending on how serious this project is, usable ribbons can be had for less than a 100 euros. Just make sure to check the ribbon for slack if you get one.
For example, I use one of these as a roommic when going for vibes every now and then and it has worked pretty well so far.
http://www.thomann.de/nl/the_tbone_rm700.htm
And also +1 on using tons of colour comps and EQ. Especially since the recording equipment isn't vintage at all, it will probably need some compensation.