1979 351 Windsor Horsepower?
When working with any car manufactures engines ID the engine first.
On the block there will be a casting number.
order of info is"
year of manufacture
Type of Vehicle it was installed in
Brand of Vehicle it was installed in
Special information for additional ID'ing of engine
Casting Number DF92
69-74 351W 5.8 H Ford, Mercury, 7/16" Holes In Head For P.S., W/O Smog, 8 Bolt Intake Manifold.
Casting Number DF41
75-78 351W 5.8 G,H Ford, Mercury, Studded Heads or Bolt Down Rockers, Smog heads.
Casting Number DF34
77-87 351W 5.8 H,G Ford, Mercury, Studded Heads or Bolt Down Rockers, 4BBL WO/HO, 6 Bolt Intake Manifold.
Casting Number DF15
77-87 351W 5.8 H,G Ford, Mercury, Truck & Van, 3 Bolt Holes For A.C. & P.S., Studded Heads or Bolt Down Rockers, Side Smog, NOTE: Side smog means aspirator tube comes out of the side of head. Necessary for vans with small engine compartments, 6 Bolt Intake Manifold.
Once you have ID's the casting of both the engine block and the Heads (the heads will have different numbers) you can then determine what the original horsepower rating of the engine was by phoning a Ford dealer and asking them.