So I was thinking about kitbashing a Beast Machines Snarl (or rather, the more robust Universe redeco) so that instead of having a slashing gimmick in his right arm, he has another punching gimmick.

Is the idea too advantageous or flat out impossible, especially for a novice to minor kitbashing? Or with enough care and patience, can I gut and replace the entire gimmick of Snarl's right arm?