Unfortunately "HO" in the case of 351W's in Ford trucks and vans means nothing but a crossbreed Holley 4bbl carburetor and a cam designed to produce low to moderate RPM torque.
Just a generic 351W otherwise. With a moderate price rebuild and careful parts choosing/shopping you can look for 300 HP. 350HP maybe if you're good. This is assuming you are going to do as much of the needed work as possible yourself. Throw buckets of money at it and you can make lots more. If you pretty well have to pay for all the work done on the rebuild, just your most basic stock rebuild will pretty well blow your budget.