Only standard definition CRT and make sure it doesn't have any fancy built in processing (line doubler or progressive scan)
I have a 36" Sony HD CRT that I picked up to use with light guns and can't because the built in line doubler can't be turned off.
There used to be standard definition CRT projection TVs back in the day that would work, but it's highly unlikely you'd find one that would work. They weren't that reliable and are expensive to fix. They also usually had the built in processing that screws light guns up.
If I were you, I'd look for a basic model 36" tube tv on craigslist or ebay.
If you hold out, you can probably find one for free.