Gear Ratios?

Is your car a manual?

I'm not totally sure about the pre-87's, but I'd venture a guess that your car probably has the 3.45 gears in the rear (those were standard issue behind the manual trans in Mustangs and Thunderbirds for several years)

SVO's had 3.73 gears (same as 5 speed 2.3L Mustangs), but they had different transmission ratios than other 2.3L cars. .78 OD, according to this chart, which is pretty handy: http://www.fordmuscle.com/archives/2000/09/t5swap/index2.shtml

My TC has 3.55's in it (of course, 8.8 rear) and I think they're about perfect behind a 2.3T.

I think your going to be fine. SVO IIRC had 3.73: 1 gears and with 5th gear it should get snappy acceleration and yet still get good economy in 5th.

Heres some siites I have bookmarked that might come in handy for you

http://www.ricksontruck.com/calculators.html

http://www.miata.net/garage/tirecalc.html