An easy way to tell a 351C head is the canted valves and they flow water differently than 351W heads do. 351C has the water neck in the block not the intake.
A lot of work would have been needed to make 351c heads fit a 302... the e7te part number is for a set of 351w truck heads, also used on the 87-93 5.0 HO engines.
They are junk. What you want are gt40 heads you can source them from any 5.0 explorer engine. Vastly superior to what you have now.
Yeah, sorry to tell ya, but you've got nothing special there. Those are 351W truck heads. The only difference between the 302/351W heads is the 351W heads are drilled for 1/2" head bolts. They provide zero performance improvement over your stock heads.
Like a91what said,if you're looking for a performance boost on a budget, look for Asher of 5.0 Explorer heads and intake.