My brother has a 1988 Bronco with the 302 engine as well.
I'm curious, what's the hp and torque rating of the 302 anyway?
Doing all those modifications cost a lot of money.
Your best bet would just be to sell the Bronco and find one with the 351 V-8.
That should solve your towing issues.
I'd imagine finding a 1988 or so Bronco in similiar condition as your current Bronco but with the 351 would only be a few hundred dollars more.
Then if you still need more power, add Flowmasters, intake to the 351 and you should be alright.
Another thing, if your riding on large (32" or bigger tires) get rid of them.
They raise your axle ratio and make the truck too slow.
Smaller diameter wheels/tires, though not looking as "cool" give you a better axle ratio, are less rotational mass, and therefore makes the truck/car perform better.