The Cobra Mustang (during that era) was produced under the auspices of SVT. If it's '95 model SVT Cobra or Cobra R, engine was either a 5.0 (302) or 5.8 (351) V-8, the old pushrod engine. This was the last year for the pushrod V-8 in a Mustang. It's visually very easy to tell these old engines from the new "modular" 4.6/5.4 OHC engines, which have much wider valve covers, for one.
Again, this assumes the engine you're dealing with is in fact an SVT Cobra engine - and is correct for the year (1995).
From what you describe, it sounds like it's not the correct engine for the year, since it appears to be a 4.6 (which first came out in the Mustang the next year, 1996).
Later SVT versions of the 4.6 had three valve heads, I think - so that may be one way to figure out whether that's what you have..