I have the U500 4 iron and I love it and would definitely consider a 3 iron too. Unfortunately the U500 is no longer in production, it has been replaced with the U505 and T200 utility build. You may still find some old stock of the U500 but I'm pretty sure a custom build is not possible anymore. The t200 utility build is the replacement, but I'm not sure how that stacks up against the U500.

If you can find a U500 in your spec then go for it, you wont regret it. I found the 2 iron U500 easy to hit so the 3 will be fine!

I've got a U500 3 iron. I think it was a pretty good buy - it remains in the bag and will do so for the foreseeable future. Mainly use it off the tee - it's particularly good for stingers and narrow fairways - but also occasionally from good lies in the first cut.
Don't think you'll have any difficulty finding one if you want one (Golfbidder, for example, has several).
The general spec was a Hzrdus Smoke shaft in a small range of flex's.

Have also tried a new U505 and it was fairly similar in terms of feel and performance.

Don't think you'll be disappointed but the trick is to try all the options (U500, U505 & T200) and go for what suits you best. Good luck.
JT

My advice would be, go and get fit.
I was hitting the T200 better than my U500 4 iron, higher and longer.I’m going to buy the T200 3 iron to match my set with Project X LZ 6,0 not the standard Hzrdus RDX.
Regards
Gary