A manual shift valve body may make it shift hard but unless it is a valve body that applies the low/reverse band in low range it is not good to use on the street. Many guys have ran them and got lucky and not trashed their trannies but I wouldn't take a chance with one.
Like EricS68 said it sounds like you only need a solid built trans with a good shift improver kit in it such as Trans-go's TF-2 kit. A manual valve body is overkill for someone who's race use is only at 10%.
Oh and the reason for a reverse valve body is so when you are shifting gears you are shifting away from neutral. So "reverse shifting" and "slap shifting" don't mean the same thing.