efficiency calculation correct?

Made my first AG yesterday. EdWort's Kolsch with additional grain to correct for my expected less than optimal efficiency.

7.0 increased to 8.8 lbs of 2 row pilsner malt
8.8 x 36 = 316.8

2.5 increased to 3.2 lbs of wheat malt
3.2 x 39 = 124.8

316.8 + 124.8 = 441.6

441.6/5.25 gallons = 84.11

actual OG was 1.051

51/84.11 = 60%

Does that look correct?

Just for info:
I used a 10 gallon rubbermaid water cooler with the braided line kit.

I used 3.75 gallons of strike water at 185. I let the water sit for 5 minutes to heat cooler before proceeding. Water was 175 when I added grain and doughed in.

at 5 minutes I opened up restirred and added a little tap water to drop temperature. It was 160 and about 1.5 cups brought it down to 154.

at 60 minutes I collected 2 qts, added to top and then drained into boil pot. I collected 2.5 gallons so figured I needed another 4.5 gallons of sparge water to total 6.5 for boil. All sparge waster was done at 180

Stirred in 2.0 gallons, waited 10 minutes, drained and added 2 qts and collected into boil pot.

Stirred in remaining 2.5 gallons, waited 10 minutes, drained and added 2 qts and collected into boil pot.

OG at that point for 6.5 gallons was 1.044 at 60

That is a bit hot to dough in at 175F. You are denaturing grains at 170F? Are you using a program to figure strike temperature? I would think that 166F to 167F strike water is a good starting point with the mash-tun stabilized at that temperature.

I went back and looked at my cheat sheet and it did say let it cool to 168 but I guess I was worried about how quickly it would cool. In retrospect, it only dropped to 175 and even after doughing in, and waiting 5 minutes, it was still 160 requiring me to add cool water.

Would denaturing the grain affect the taste or make me lose efficiency or both?

If you denature grain then you have no conversion of starches to sugar and little to nothing to ferment.

Read here: How to Brew - By John Palmer - How the Mash Works