I am trying to decide on a racing wheelset and have a few options, but don't know which one is best for the riding i do. 135lbs, avg. 23mph on a road bike for sprint distance, but will be putting in a lot more training before i get to race these wheels much, looking mostly for ironman california 70.3 and coeur d'alene.

either a hed rear disc and tri spoke front (both hed clincher),
a tubular hed disc and tubular 404 set,
just the 404 set
a rear 808 and front 404

all options are under $1000 total

any advice is helpful

It really depends on the majority of the conditions you will be racing in, if it is windy, and/or hilly, 404 front 808 rear is about the most versatile combo out there, (you don't want anything shallower than an 808 in back, so don't worry about the 404 set), If it is not hilly or windy, then go with the HED disk/trispoke combo, it is more aero, but you might get jossled around in major crosswinds (for instance if you are preparing for kona, not even the pros use disks.

even if you race hills a lot, i'd still go with the disk/trispoke combo. i would use a disk at both cal 70.3 and imcda. only avoid the disk if you race a lot in very windy conditions.

I'd say the 404 set and rear disc. The 404 set is an amazing all around wheel set for any type of race. I currently have stinger 60's on my tri bike and have loved them. They have be sufficient thru all my races especially some of the hillier ones.

I think having the 404 set and a rear disc would be the most versatile you could get and you'll have the most options as far as race use.

thanks. that's what i was leaning towards, especially since its the same price as the disc/h3 combo would have been. just wanted other opinions.

I have a set of clincher Hed 3's and this is the first, maybe second year that I've ever been able to say this:

They just are outdated.

Now mind you, here is what I think of them for the most part:

They are aerodynamically great. Still are, thats why I've hung on to mine.
They are not terribly heavy, but also not light.
They are not the most comfortable wheel. Normally we think, "ohhh carbon, it dampens vibrations", not in this case.
They are flexible in corners.
They require 20mm tires to be at their aerodynamic best, which really doesn't help the point about the comfort.

Quite frankly, they are only really starting to lose ground because Hed has come out with their wide rim technology, which essentially makes wheels perform better with wider tires, is more comfortable and they corner better. However, these wheels are not particularly faster than the now 15 year old Hed trispoke design.

I think I've said it before around here but when it comes to wheel selection a no-brainer is this:
1. Disc in the rear
2. Deepest front you are comfortable with in cross winds. (I weigh the same as you and ride a Hed 3 which is a beast in cross winds, so don't be afraid to try out a 80-90mm deep wheel)
3. Which ever you can change faster clincher or tubular in the event of a flat.

One things for sure, get whatever you think will be best. Once you have what you think is best, that is essentially the best wheel for you because it is the wheelset you are least likely to worry about when you should be worrying about racing.