I've never owned a Nova but can't see any reason why you'd put a 235 in one. In a head-to-head comparison the 250 has it beat hands down. More power, better design, MUCH lighter weight, higher HP potential, etc.
But from a practical standpoint the 2 biggest problems I see are (as you've already mentioned) motor mounts and overall fitment. The 235 is a very tall motor and the Nova engine bay isn't very well suited to handle it. I can definitely see some fabrication work necessary to make this engine fit.
In fact, the amount of work to benefit ratio is so low that many inliners are probably going to discourage even trying it.
-magic mike-
