FT snowball rolls hard right and dives, HELP

DTFB construction is usually hot glue and tape away from just one more flight.
no need for pretty .. it just has to fly.
So your flying an old Futaba Conquest .... I'm not even sure you can still legally use that as it may predate narrow band standards.
Not that I intend to lecture you about it, but keep it in mind so you don't get pinched for it.
your right .. nope, it won't fly the Arrow ... which is unfortunate. It is a brilliant balance of fast easy build and flight performance.
Its worth getting a radio that can mix as soon as practical. much of the FT fleet makes use of mixing.
Till then, and for as long as you don't get pinched over your radio, Simple soarer, Old Fogey and tiny trainer, and explorer might be worth looking into.
a little more sophistication over the nutball design gives you better flight characteristics. if your running a radio as old as a Conquest, my guess is you are very new to this.
quirky aircraft are ok after you have the skill to deal with some of the curve balls these super simple designs often throw at you.