I assume you have a single overhead cam engine. I could be wrong, but I dont think swapping in a 98+ engine is feasible since it is a Double overhead cam engine (DOHC). I assume the engine wiring is different.

Some things I would suggest:

Parting out the truck or selling it 'as is' is not going to be a whole lot of money. Expect to get little return on that. Isuzu's terrible resale value and low demand for used parts are working against you here.

if you have the cash, and I were you, I'd look for another Rodeo. Like I said resale value can work in your favor for picking up another one pretty cheap. You can get a 98+ on ebay for under 7k.

my .02