Currently, during transaction tests that attempt to overflow the gasPrice and Value fields using values equal to or greater than 2**256, the transactions are accepted as valid.
The suggested feature change is that t9n rejects values greater than or equal to 2**256 in these fields.
The impact of this change to block validation should be none since, in actuality, no account can have a balance greater than these values and the transactions should end up being rejected anyway, but the benefit of this change is for testing purposes only.