Originally Posted by RobbieTunes

Yes, this, +1.

Tubing: Comp TA has Tange 2 vs. Ironman Tange 1. 99.9% of us would not know the difference. At your sizes, less than 2 oz of weight difference. Call it a wash.
Geometry: Comp TA is slightly more relaxed vs. Ironman. More stable. More comfortable on longer rides. Not as quick to change lines in a pace line. Call it a wash.
Fork: Comp TA has the pretty sloped internal lugged crown, the Ironman has a unicrown, as it's an Expert model, given the red and white. Slight advantage, Comp TA.
DT braze-ons: Comp TA has the older Shimano braze-ons that can require mods to build with late-80's stuff. Ironman has more normal braze-ons. Advantage, Ironman.
Graphics: Comp TA is the elegant font and much more subtle, metallic colors. Ironman is more modern Let's Race Red and White. A wash, more a matter of preference.
Colors: Comp TA's subdued hues match silver components, but not as well for modern and black. Ironman is good with about anything. Advantage, Ironman.
Uniquity: You are not going to see very many of those Comp TA's. BF Goodrich made sure of that. There are Ironman everywhere. For good reason: quality for the $.
Street Cred: An Ironman rider does not have to explain that his bike is the predecessor to the Ironman. A Comp TA is not an aphrodesiac, but the Ironman, whoa Nelly.

That being said: FIT IS EVERYTHING. I'd say ride them both. One is 2cm shorter on the ST, but 1 cm shorter on the TT. This is quite adjustable, but you need to decide which Fit is the best, given the seatposts, stems, and bars at your disposal. Set them up, ride them, and listen to your body. Consider the distances you will be riding, as well. Under 20 miles, fit is "there," but not nagging you. At 40 miles, fit becomes more essential, as your body will definitely let you know. At that point, you have to decide if aches/pains are fitness or fit.

I'm allegedly an Ironman junkie, but I've owned a Comp TA and really liked it. The '84 Comp TA and the '85 Ironman, other than tubing, are pretty much interchangeable in my mind, and if I never find the elusive '85 in my size, I've no problem getting a Comp TA instead. Whichever I come across first, likely I'd pick up. The Ironman is, of course, instantly recognizeable, and has a fan base. Both came with easily found components, and both frames are quite good enough to really show you their stuff on trued and tensioned wheelsets and well-lubed, well-adjusted components. Upgrades to modern on either will blow you away with the quality of the frame.

Luckily, I am not in the market for a TA that size, nor an Ironman that year or even that color. This allows me to post without bias (yeah, right).

Seriously, Go with the one that fits, though, and once you're there, put the best group you have on it, dress up the other one pretty and sell it.