If I remember correctly the 225 is a Buick with a Buick bolt pattern. The adapter that comes in the Jeep might not work with a 4.3 or a 350 Chev. A popular conversion would be either engine with a sm420 or 465 to your 18 case. If you dont like the odd fire V6 (225) I think the even fire 231 V6 will bolt in. My uncle used to run a 300 hp 225 when he was sand dragging. So the power can be achieved if you want to spend the money. He later dropped it down to about 200 hp to make it better off road when they quit racing. Also remember with the conversions the drive line start getting pretty short since you only have a 80 inch wheelbase.