I'm running a 502HO crate motor in a 68 Camaro with a TH400. I have 3.55 rear gears and 28" tall tires. The engine makes peak power at 3500 rpm, but all I seem to find in that range say "not for big-block".  
Any suggestions are appreciated.  

The engine makes peak TORQUE at 3500 I'm sure, so probably a 2500 converter would be best. But really even a stock converter wouldn't be too much of a disadvantage with all the torque that engine will make down low. If this is primarily a street machine that won't see a drag strip I wouldn't go up to 2500, if you're concerned with your launch you can try it...  

Thanks for the correction and Sorry about that.  I should have said that the advertised hp peak is at 5250 and the advertised torque peak is at 3500. The TH400 was out of a 78 Suburban and the current converter is a Sat night special that's supposed to be 1000 over stock or around 2800 stall. I was just trying to match the torque a little more closely. The car spends most of it's time on the street, but does see the 1/4 mile track several times a year.  

I don't want to bad mouth anyone,but I do like to pass along advice learned first hand.I'd stay away from ACC's Boss Hogg converters.Had terrible luck with mine and so did my buddy.  

torque on the 502HO runs a flat, 480 ft-lbs from 1750 to 2500 rpm, at that point, it starts ramping up to peak out at 550 ft-lbs @ 3500 rpm. stalling at the bottom of the ramp is going to give you the best power for launching. i'm using  the TCI 11" #240900 with my ZZ502, it stalls at 2650 in an el camino (3700 lbs). in a lighter car with slightly less torque, it should stall a couple of hundred r's less. camaro is lighter isn't it? i've never owned one but i seem to remember it is.
anyway, my set-up is very close to what you're running, 3.50 gears with 28" tall tires, so you'll have about the same results. it's a loose enough converter to take advantage of your powerband, but tight enough to cruise around town. mine has performed flawlessly for the last 4 years so it will take everything your 502HO has.